Problem: Recently Vasya got interested in finding extra-terrestrial intelligence. He made a simple extra-terrestrial signals’ receiver and was keeping a record of the signals for n days in a row. Each of those n days Vasya wrote a 1 in his notebook if he had received a signal that day and a 0 if he hadn’t. Vasya thinks that he has found extra-terrestrial intelligence if there is a system in the way the signals has been received, i.e. if all the intervals between successive signals are equal. Otherwise, Vasya thinks that the signals were sent by some stupid aliens no one cares about. Help Vasya to deduce from the information given by the receiver if he has found extra-terrestrial intelligence or not.

Input

The first line contains integer n (3 ≤ n ≤ 100) — amount of days during which Vasya checked if there were any signals. The second line contains n characters 1 or 0 — the record Vasya kept each of those n days. It’s guaranteed that the given record sequence contains at least three 1s.

Output

If Vasya has found extra-terrestrial intelligence, output YES, otherwise output NO.

Examples

Input

8
00111000


Output

YES


Input

7
1001011


Output

NO


Input

7
1010100


Output

YES

Solution (in JAVA):

Solution:
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StreamTokenizer;
import java.io.Writer;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.Random;
import java.util.Set;
import java.util.Stack;
import java.util.TreeSet;
import java.util.Vector;

public class Abra {
        public static void main(String[] args) throws IOException {
                new Abra().run();
        }
        
        static class myLib{
                long fact(long x) {
                        long a = 1;
                        for (long i = 2; i <= x; i++) {
                                a *= i;
                        }
                        return a;
                }

                long digitSum(String x) {
                        long a = 0;
                        for (int i = 0; i < x.length(); i++) {
                                a += x.charAt(i) - '0';
                        }
                        return a;
                }

                long digitSum(long x) {
                        long a = 0;
                        while (x > 0) {
                                a += x % 10;
                                x /= 10;
                        }
                        return a;
                }

                long digitMul(long x) {
                        long a = 1;
                        while (x > 0) {
                                a *= x % 10;
                                x /= 10;
                        }
                        return a;
                }

                int digitCubesSum(int x) {
                        int a = 0;
                        while (x > 0) {
                                a += (x % 10) * (x % 10) * (x % 10);
                                x /= 10;
                        }
                        return a;
                }

                double pif(double ax, double ay, double bx, double by) {
                        return Math.sqrt((ax - bx) * (ax - bx) + (ay - by) * (ay - by));
                }

                long gcd(long a, long b) {
                        if (a == 0 || b == 0) return 1;
                        if (a < b) {
                                long c = b;
                                b = a;
                                a = c;
                        }
                        while (a % b != 0) {
                                a = a % b;
                                if (a < b) {
                                        long c = b;
                                        b = a;
                                        a = c;
                                }
                        }
                        return b;
                }

                int gcd(int a, int b) {
                        if (a == 0 || b == 0) return 1;
                        if (a < b) {
                                int c = b;
                                b = a;
                                a = c;
                        }
                        while (a % b != 0) {
                                a = a % b;
                                if (a < b) {
                                        int c = b;
                                        b = a;
                                        a = c;
                                }
                        }
                        return b;
                }

                long lcm(long a, long b) throws IOException {
                        return a * b / gcd(a, b);
                }

                int lcm(int a, int b) throws IOException {
                        return a * b / gcd(a, b);
                }

                int countOccurences(String x, String y) {
                        int a = 0, i = 0;
                        while (true) {
                                i = y.indexOf(x);
                                if (i == -1) break;
                                a++;
                                y = y.substring(i + 1);
                        }
                        return a;
                }

                int[] findPrimes(int x) {
                        boolean[] forErato = new boolean[x - 1];
                        List<Integer> t = new Vector<Integer>();
                        int l = 0, j = 0;
                        for (int i = 2; i < x; i++) {
                                if (forErato[i - 2]) continue;
                                t.add(i);
                                l++;
                                j = i * 2;
                                while (j < x) {
                                        forErato[j - 2] = true;
                                        j += i;
                                }
                        }
                        int[] primes = new int[l];
                        Iterator<Integer> iterator = t.iterator();
                        for (int i = 0; iterator.hasNext(); i++) {
                                primes[i] = iterator.next().intValue();
                        }
                        return primes;
                }

                int rev(int x) {
                        int a = 0;
                        while (x > 0) {
                                a = a * 10 + x % 10;
                                x /= 10;
                        }
                        return a;
                }

                class myDate {
                        int d, m, y;

                        int[] ml = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

                        public myDate(int da, int ma, int ya) {
                                d = da;
                                m = ma;
                                y = ya;
                                if ((ma > 12 || ma < 1 || da > ml[ma - 1] || da < 1) && !(d == 29 && m == 2 && y % 4 == 0)) {
                                        d = 1;
                                        m = 1;
                                        y = 9999999;
                                }
                        }

                        void incYear(int x) {
                                for (int i = 0; i < x; i++) {
                                        y++;
                                        if (m == 2 && d == 29) {
                                                m = 3;
                                                d = 1;
                                                return;
                                        }
                                        if (m == 3 && d == 1) {
                                                if (((y % 4 == 0) && (y % 100 != 0)) || (y % 400 == 0)) {
                                                        m = 2;
                                                        d = 29;
                                                }
                                                return;
                                        }
                                }
                        }

                        boolean less(myDate x) {
                                if (y < x.y) return true;
                                if (y > x.y) return false;
                                if (m < x.m) return true;
                                if (m > x.m) return false;
                                if (d < x.d) return true;
                                if (d > x.d) return false;
                                return true;
                        }

                        void inc() {
                                if ((d == 31) && (m == 12)) {
                                        y++;
                                        d = 1;
                                        m = 1;
                                } else {
                                        if (((y % 4 == 0) && (y % 100 != 0)) || (y % 400 == 0)) {
                                                ml[1] = 29;
                                        }
                                        if (d == ml[m - 1]) {
                                                m++;
                                                d = 1;
                                        } else
                                                d++;
                                }
                        }
                }

                int partition(int n, int l, int m) {// n - sum, l - length, m - every part
                        // <= m
                        if (n < l) return 0;
                        if (n < l + 2) return 1;
                        if (l == 1) return 1;
                        int c = 0;
                        for (int i = Math.min(n - l + 1, m); i >= (n + l - 1) / l; i--) {
                                c += partition(n - i, l - 1, i);
                        }
                        return c;
                }

                int rifmQuality(String a, String b) {
                        if (a.length() > b.length()) {
                                String c = a;
                                a = b;
                                b = c;
                        }
                        int c = 0, d = b.length() - a.length();
                        for (int i = a.length() - 1; i >= 0; i--) {
                                if (a.charAt(i) == b.charAt(i + d)) c++;
                                else
                                        break;
                        }
                        return c;
                }

                String numSym = "0123456789ABCDEF";

                String ZFromXToYNotation(int x, int y, String z) {
                        if (z.equals("0")) return "0";
                        String a = "";
                        long q = 0, t = 1;
                        for (int i = z.length() - 1; i >= 0; i--) {
                                q += (z.charAt(i) - 48) * t;
                                t *= x;
                        }
                        while (q > 0) {
                                a = numSym.charAt((int) (q % y)) + a;
                                q /= y;
                        }
                        return a;
                }

                double angleFromXY(int x, int y) {
                        if ((x == 0) && (y > 0)) return Math.PI / 2;
                        if ((x == 0) && (y < 0)) return -Math.PI / 2;
                        if ((y == 0) && (x > 0)) return 0;
                        if ((y == 0) && (x < 0)) return Math.PI;
                        if (x > 0) return Math.atan((double) y / x);
                        else {
                                if (y > 0) return Math.atan((double) y / x) + Math.PI;
                                else
                                        return Math.atan((double) y / x) - Math.PI;
                        }
                }

                static boolean isNumber(String x) {
                        try {
                                Integer.parseInt(x);
                        } catch (NumberFormatException ex) {
                                return false;
                        }
                        return true;
                }

                static boolean stringContainsOf(String x, String c) {
                        for (int i = 0; i < x.length(); i++) {
                                if (c.indexOf(x.charAt(i)) == -1) return false;
                        }
                        return true;
                }

                long pow(long a, long n) { // b > 0
                        if (n == 0) return 1;
                        long k = n, b = 1, c = a;
                        while (k != 0) {
                                if (k % 2 == 0) {
                                        k /= 2;
                                        c *= c;
                                } else {
                                        k--;
                                        b *= c;
                                }
                        }
                        return b;
                }

                int pow(int a, int n) { // b > 0
                        if (n == 0) return 1;
                        int k = n, b = 1, c = a;
                        while (k != 0) {
                                if (k % 2 == 0) {
                                        k /= 2;
                                        c *= c;
                                } else {
                                        k--;
                                        b *= c;
                                }
                        }
                        return b;
                }

                double pow(double a, int n) { // b > 0
                        if (n == 0) return 1;
                        double k = n, b = 1, c = a;
                        while (k != 0) {
                                if (k % 2 == 0) {
                                        k /= 2;
                                        c *= c;
                                } else {
                                        k--;
                                        b *= c;
                                }
                        }
                        return b;
                }

                double log2(double x) {
                        return Math.log(x) / Math.log(2);
                }

                int lpd(int[] primes, int x) {// least prime divisor
                        int i;
                        for (i = 0; primes[i] <= x / 2; i++) {
                                if (x % primes[i] == 0) {
                                        return primes[i];
                                }
                        }
                        ;
                        return x;
                }

                int np(int[] primes, int x) {// number of prime number
                        for (int i = 0; true; i++) {
                                if (primes[i] == x) return i;
                        }
                }

                int[] dijkstra(int[][] map, int n, int s) {
                        int[] p = new int[n];
                        boolean[] b = new boolean[n];
                        Arrays.fill(p, Integer.MAX_VALUE);
                        p[s] = 0;
                        b[s] = true;
                        for (int i = 0; i < n; i++) {
                                if (i != s) p[i] = map[s][i];
                        }
                        while (true) {
                                int m = Integer.MAX_VALUE, mi = -1;
                                for (int i = 0; i < n; i++) {
                                        if (!b[i] && (p[i] < m)) {
                                                mi = i;
                                                m = p[i];
                                        }
                                }
                                if (mi == -1) break;
                                b[mi] = true;
                                for (int i = 0; i < n; i++)
                                        if (p[mi] + map[mi][i] < p[i]) p[i] = p[mi] + map[mi][i];
                        }
                        return p;
                }

                boolean isLatinChar(char x) {
                        if (((x >= 'a') && (x <= 'z')) || ((x >= 'A') && (x <= 'Z'))) return true;
                        else
                                return false;
                }

                boolean isBigLatinChar(char x) {
                        if (x >= 'A' && x <= 'Z') return true;
                        else
                                return false;
                }

                boolean isSmallLatinChar(char x) {
                        if (x >= 'a' && x <= 'z') return true;
                        else
                                return false;
                }

                boolean isDigitChar(char x) {
                        if (x >= '0' && x <= '9') return true;
                        else
                                return false;
                }

                class NotANumberException extends Exception {
                        private static final long serialVersionUID = 1L;
                        String mistake;

                        NotANumberException() {
                                mistake = "Unknown.";
                        }

                        NotANumberException(String message) {
                                mistake = message;
                        }
                }

                class Real {
                        String num = "0";
                        long exp = 0;
                        boolean pos = true;

                        long length() {
                                return num.length();
                        }

                        void check(String x) throws NotANumberException {
                                if (!stringContainsOf(x, "0123456789+-.eE")) throw new NotANumberException("Illegal character.");
                                long j = 0;
                                for (long i = 0; i < x.length(); i++) {
                                        if ((x.charAt((int) i) == '-') || (x.charAt((int) i) == '+')) {
                                                if (j == 0) j = 1;
                                                else
                                                        if (j == 5) j = 6;
                                                        else
                                                                throw new NotANumberException("Unexpected sign.");
                                        } else
                                                if ("0123456789".indexOf(x.charAt((int) i)) != -1) {
                                                        if (j == 0) j = 2;
                                                        else
                                                                if (j == 1) j = 2;
                                                                else
                                                                        if (j == 2)
                                                                        ;
                                                                        else
                                                                                if (j == 3) j = 4;
                                                                                else
                                                                                        if (j == 4)
                                                                                        ;
                                                                                        else
                                                                                                if (j == 5) j = 6;
                                                                                                else
                                                                                                        if (j == 6)
                                                                                                        ;
                                                                                                        else
                                                                                                                throw new NotANumberException("Unexpected digit.");
                                                } else
                                                        if (x.charAt((int) i) == '.') {
                                                                if (j == 0) j = 3;
                                                                else
                                                                        if (j == 1) j = 3;
                                                                        else
                                                                                if (j == 2) j = 3;
                                                                                else
                                                                                        throw new NotANumberException("Unexpected dot.");
                                                        } else
                                                                if ((x.charAt((int) i) == 'e') || (x.charAt((int) i) == 'E')) {
                                                                        if (j == 2) j = 5;
                                                                        else
                                                                                if (j == 4) j = 5;
                                                                                else
                                                                                        throw new NotANumberException("Unexpected exponent.");
                                                                } else
                                                                        throw new NotANumberException("O_o.");
                                }
                                if ((j == 0) || (j == 1) || (j == 3) || (j == 5)) throw new NotANumberException("Unexpected end.");
                        }

                        public Real(String x) throws NotANumberException {
                                check(x);
                                if (x.charAt(0) == '-') pos = false;
                                long j = 0;
                                String e = "";
                                boolean epos = true;
                                for (long i = 0; i < x.length(); i++) {
                                        if ("0123456789".indexOf(x.charAt((int) i)) != -1) {
                                                if (j == 0) num += x.charAt((int) i);
                                                if (j == 1) {
                                                        num += x.charAt((int) i);
                                                        exp--;
                                                }
                                                if (j == 2) e += x.charAt((int) i);
                                        }
                                        if (x.charAt((int) i) == '.') {
                                                if (j == 0) j = 1;
                                        }
                                        if ((x.charAt((int) i) == 'e') || (x.charAt((int) i) == 'E')) {
                                                j = 2;
                                                if (x.charAt((int) (i + 1)) == '-') epos = false;
                                        }
                                }
                                while ((num.length() > 1) && (num.charAt(0) == '0'))
                                        num = num.substring(1);
                                while ((num.length() > 1) && (num.charAt(num.length() - 1) == '0')) {
                                        num = num.substring(0, num.length() - 1);
                                        exp++;
                                }
                                if (num.equals("0")) {
                                        exp = 0;
                                        pos = true;
                                        return;
                                }
                                while ((e.length() > 1) && (e.charAt(0) == '0'))
                                        e = e.substring(1);
                                try {
                                        if (e != "") if (epos) exp += Long.parseLong(e);
                                        else
                                                exp -= Long.parseLong(e);
                                } catch (NumberFormatException exc) {
                                        if (!epos) {
                                                num = "0";
                                                exp = 0;
                                                pos = true;
                                        } else {
                                                throw new NotANumberException("Too long exponent");
                                        }
                                }
                        }

                        public Real() {
                        }

                        String toString(long mantissa) {
                                String a = "", b = "";
                                if (exp >= 0) {
                                        a = num;
                                        if (!pos) a = '-' + a;
                                        for (long i = 0; i < exp; i++)
                                                a += '0';
                                        for (long i = 0; i < mantissa; i++)
                                                b += '0';
                                        if (mantissa == 0) return a;
                                        else
                                                return a + "." + b;
                                } else {
                                        if (exp + length() <= 0) {
                                                a = "0";
                                                if (mantissa == 0) {
                                                        return a;
                                                }
                                                if (mantissa < -(exp + length() - 1)) {
                                                        for (long i = 0; i < mantissa; i++)
                                                                b += '0';
                                                        return a + "." + b;
                                                } else {
                                                        if (!pos) a = '-' + a;
                                                        for (long i = 0; i < mantissa; i++)
                                                                if (i < -(exp + length())) b += '0';
                                                                else
                                                                        if (i + exp >= 0) b += '0';
                                                                        else
                                                                                b += num.charAt((int) (i + exp + length()));
                                                        return a + "." + b;
                                                }
                                        } else {
                                                if (!pos) a = "-";
                                                for (long i = 0; i < exp + length(); i++)
                                                        a += num.charAt((int) i);
                                                if (mantissa == 0) return a;
                                                for (long i = exp + length(); i < exp + length() + mantissa; i++)
                                                        if (i < length()) b += num.charAt((int) i);
                                                        else
                                                                b += '0';
                                                return a + "." + b;
                                        }
                                }
                        }
                }

                boolean containsRepeats(int... num) {
                        Set<Integer> s = new TreeSet<Integer>();
                        for (int d : num)
                                if (!s.contains(d)) s.add(d);
                                else
                                        return true;
                        return false;
                }

                int[] rotateDice(int[] a, int n) {
                        int[] c = new int[6];
                        if (n == 0) {
                                c[0] = a[1];
                                c[1] = a[5];
                                c[2] = a[2];
                                c[3] = a[0];
                                c[4] = a[4];
                                c[5] = a[3];
                        }
                        if (n == 1) {
                                c[0] = a[2];
                                c[1] = a[1];
                                c[2] = a[5];
                                c[3] = a[3];
                                c[4] = a[0];
                                c[5] = a[4];
                        }
                        if (n == 2) {
                                c[0] = a[3];
                                c[1] = a[0];
                                c[2] = a[2];
                                c[3] = a[5];
                                c[4] = a[4];
                                c[5] = a[1];
                        }
                        if (n == 3) {
                                c[0] = a[4];
                                c[1] = a[1];
                                c[2] = a[0];
                                c[3] = a[3];
                                c[4] = a[5];
                                c[5] = a[2];
                        }
                        if (n == 4) {
                                c[0] = a[0];
                                c[1] = a[2];
                                c[2] = a[3];
                                c[3] = a[4];
                                c[4] = a[1];
                                c[5] = a[5];
                        }
                        if (n == 5) {
                                c[0] = a[0];
                                c[1] = a[4];
                                c[2] = a[1];
                                c[3] = a[2];
                                c[4] = a[3];
                                c[5] = a[5];
                        }
                        return c;
                }

                int min(int... a) {
                        int c = Integer.MAX_VALUE;
                        for (int d : a)
                                if (d < c) c = d;
                        return c;
                }

                int max(int... a) {
                        int c = Integer.MIN_VALUE;
                        for (int d : a)
                                if (d > c) c = d;
                        return c;
                }

                int[] normalizeDice(int[] a) {
                        int[] c = a.clone();
                        if (c[0] != 0) if (c[1] == 0) c = rotateDice(c, 0);
                        else
                                if (c[2] == 0) c = rotateDice(c, 1);
                                else
                                        if (c[3] == 0) c = rotateDice(c, 2);
                                        else
                                                if (c[4] == 0) c = rotateDice(c, 3);
                                                else
                                                        if (c[5] == 0) c = rotateDice(rotateDice(c, 0), 0);
                        while (c[1] != min(c[1], c[2], c[3], c[4]))
                                c = rotateDice(c, 4);
                        return c;
                }

                boolean sameDice(int[] a, int[] b) {
                        for (int i = 0; i < 6; i++)
                                if (a[i] != b[i]) return false;
                        return true;
                }

                final double goldenRatio = (1 + Math.sqrt(5)) / 2;
                final double aGoldenRatio = (1 - Math.sqrt(5)) / 2;

                long Fib(int n) {
                        if (n < 0) if (n % 2 == 0) return -Math.round((pow(goldenRatio, -n) - pow(aGoldenRatio, -n)) / Math.sqrt(5));
                        else
                                return -Math.round((pow(goldenRatio, -n) - pow(aGoldenRatio, -n)) / Math.sqrt(5));
                        return Math.round((pow(goldenRatio, n) - pow(aGoldenRatio, n)) / Math.sqrt(5));
                }

                class japaneeseComparator implements Comparator<String> {
                        @Override
                        public int compare(String a, String b) {
                                int ai = 0, bi = 0;
                                boolean m = false, ns = false;
                                if (a.charAt(ai) <= '9' && a.charAt(ai) >= '0') {
                                        if (b.charAt(bi) <= '9' && b.charAt(bi) >= '0') m = true;
                                        else
                                                return -1;
                                }
                                if (b.charAt(bi) <= '9' && b.charAt(bi) >= '0') {
                                        if (a.charAt(ai) <= '9' && a.charAt(ai) >= '0') m = true;
                                        else
                                                return 1;
                                }
                                a += "!";
                                b += "!";
                                int na = 0, nb = 0;
                                while (true) {
                                        if (a.charAt(ai) == '!') {
                                                if (b.charAt(bi) == '!') break;
                                                return -1;
                                        }
                                        if (b.charAt(bi) == '!') {
                                                return 1;
                                        }
                                        if (m) {
                                                int ab = -1, bb = -1;
                                                while (a.charAt(ai) <= '9' && a.charAt(ai) >= '0') {
                                                        if (ab == -1) ab = ai;
                                                        ai++;
                                                }
                                                while (b.charAt(bi) <= '9' && b.charAt(bi) >= '0') {
                                                        if (bb == -1) bb = bi;
                                                        bi++;
                                                }
                                                m = !m;
                                                if (ab == -1) {
                                                        if (bb == -1) continue;
                                                        else
                                                                return 1;
                                                }
                                                if (bb == -1) return -1;
                                                while (a.charAt(ab) == '0' && ab + 1 != ai) {
                                                        ab++;
                                                        if (!ns) na++;
                                                }
                                                while (b.charAt(bb) == '0' && bb + 1 != bi) {
                                                        bb++;
                                                        if (!ns) nb++;
                                                }
                                                if (na != nb) ns = true;
                                                if (ai - ab < bi - bb) return -1;
                                                if (ai - ab > bi - bb) return 1;
                                                for (int i = 0; i < ai - ab; i++) {
                                                        if (a.charAt(ab + i) < b.charAt(bb + i)) return -1;
                                                        if (a.charAt(ab + i) > b.charAt(bb + i)) return 1;
                                                }
                                        } else {
                                                m = !m;
                                                while (true) {
                                                        if (a.charAt(ai) <= 'z' && a.charAt(ai) >= 'a' && b.charAt(bi) <= 'z' && b.charAt(bi) >= 'a') {
                                                                if (a.charAt(ai) < b.charAt(bi)) return -1;
                                                                if (a.charAt(ai) > b.charAt(bi)) return 1;
                                                                ai++;
                                                                bi++;
                                                        } else
                                                                if (a.charAt(ai) <= 'z' && a.charAt(ai) >= 'a') return 1;
                                                                else
                                                                        if (b.charAt(bi) <= 'z' && b.charAt(bi) >= 'a') return -1;
                                                                        else
                                                                                break;
                                                }
                                        }
                                }
                                if (na < nb) return 1;
                                if (na > nb) return -1;
                                return 0;
                        }
                }

                int mtry(String s, String alph) {
                        String t = "";
                        Random r = new Random();
                        int c = 0, l = alph.length();
                        for (int i = 0; i < s.length(); i++) {
                                t += alph.charAt(r.nextInt(l));
                                c++;
                        }
                        while (!t.equals(s)) {
                                t = t.substring(1);
                                t += alph.charAt(r.nextInt(l));
                                c++;
                        }
                        return c;
                }

                void mtest(String s, String alph, int d) {
                        int n = d, r = 0;
                        for (int i = 0; i < n; i++) {
                                r += mtry(s, alph);
                        }
                        int re = (int) Math.round((0.0 + r) / n);
                        //out.println("\"" + s + "\" = " + re + ", Average = " + ((0.0 + r) / n));
                        /*
                         * String res = Integer.toString(re); if (!tab.contains(res)) {
                         * tab.put(res, new Vector<String>()); } tab.get(res).add(s);
                         */
                }

                Random random = new Random();
        }

        StreamTokenizer in;
        PrintWriter out;
        boolean oj;
        BufferedReader br;

        void init() throws IOException {
                //oj = System.getProperty("ONLINE_JUDGE") != null;
                oj = false;
                Reader reader = oj ? new InputStreamReader(System.in) : new FileReader("input.txt");
                Writer writer = oj ? new OutputStreamWriter(System.out) : new FileWriter("output.txt");
                br = new BufferedReader(reader);
                in = new StreamTokenizer(br);
                out = new PrintWriter(writer);
        }

        long selectionTime = 0;

        void startSelection() {
                selectionTime -= System.currentTimeMillis();
        }

        void stopSelection() {
                selectionTime += System.currentTimeMillis();
        }

        void run() throws IOException {
                long beginTime = System.currentTimeMillis();
                init();
                solve();
                long endTime = System.currentTimeMillis();
                if (!oj) {
                        System.out.println("Memory used = " + (Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()));
                        System.out.println("Running time = " + (endTime - beginTime));
                        System.out.println("Time of the selection = " + selectionTime);
                }
                out.flush();
        }

        int nextInt() throws IOException {
                in.nextToken();
                return (int) in.nval;
        }

        long nextLong() throws IOException {
                in.nextToken();
                return (long) in.nval;
        }

        String nextString() throws IOException {
                in.nextToken();
                return in.sval;
        }

        double nextDouble() throws IOException {
                in.nextToken();
                return in.nval;
        }
        
        myLib lib = new myLib();
        
        void solve() throws IOException {
            int n = nextInt();
            //boolean[] a = new boolean[100];
            Vector<Integer> v = new Vector<Integer>();
            br.read();
            for (int i = 0; i < n; i++) if (br.read() == '1') v.add(i);
            Iterator<Integer> i = v.iterator();
            int q = i.next();
            int w = i.next();
            int t = w - q;
            for (; i.hasNext(); ) {
                q = w;
                w = i.next();
                if (w - q != t) {
                    out.println("NO");
                    return;
                }
            }
            out.println("YES");
        }
}