Problem: School holidays come in Berland. The holidays are going to continue for n days. The students of school №N are having the time of their lives and the IT teacher Marina Sergeyevna, who has spent all the summer busy checking the BSE (Berland State Examination) results, has finally taken a vacation break! Some people are in charge of the daily watering of flowers in shifts according to the schedule. However when Marina Sergeyevna was making the schedule, she was so tired from work and so lost in dreams of the oncoming vacation that she perhaps made several mistakes. In fact, it is possible that according to the schedule, on some days during the holidays the flowers will not be watered or will be watered multiple times. Help Marina Sergeyevna to find a mistake.

Input

The first input line contains two numbers n and m (1 ≤ n, m ≤ 100) — the number of days in Berland holidays and the number of people in charge of the watering respectively. The next m lines contain the description of the duty schedule. Each line contains two integers ai and bi (1 ≤ ai ≤ bi ≤ n), meaning that the i-th person in charge should water the flowers from the ai-th to the bi-th day inclusively, once a day. The duty shifts are described sequentially, i.e. bi ≤ ai + 1 for all i from 1 to n - 1 inclusively. 

Output

Print "OK" (without quotes), if the schedule does not contain mistakes. Otherwise you have to find the minimal number of a day when the flowers will not be watered or will be watered multiple times, and output two integers — the day number and the number of times the flowers will be watered that day.

Examples

Input

10 5
1 2
3 3
4 6
7 7
8 10


Output

OK


Input

10 5
1 2
2 3
4 5
7 8
9 10


Output

2 2


Input

10 5
1 2
3 3
5 7
7 7
7 10


Output

4 0

Note

Keep in mind that in the second sample the mistake occurs not only on the second day, but also on the sixth day, when nobody waters the flowers. However, you have to print the second day, i.e. the day with the minimal number.

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.List;
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;
                        BigInteger q = BigInteger.ZERO, t = BigInteger.ONE;
                        for (int i = z.length() - 1; i >= 0; i--) {
                                q = q.add(t.multiply(BigInteger.valueOf(z.charAt(i) - 48)));
                                t = t.multiply(BigInteger.valueOf(x));
                        }
                        while (q.compareTo(BigInteger.ZERO) == 1) {
                                a = numSym.charAt((int) (q.mod(BigInteger.valueOf(y)).intValue())) + a;
                                q = q.divide(BigInteger.valueOf(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;
                        }
                }

                Random random = new Random();
        }

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

        void init() throws IOException {
                oj = System.getProperty("ONLINE_JUDGE") != null;
                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(), m = nextInt();
        	int[] a = new int[100];
        	for (int i = 0; i < m; i++) {
        		int t1 = nextInt(), t2 = nextInt();
        		for (int j = t1; j <= t2; j++) {
        			a[j - 1]++;
        		}
        	}
        	for (int i = 0; i < n; i++) {
        		if (a[i] != 1) {
        			out.println((i + 1) + " " + a[i]);
        			return;
        		}
        	}
        	out.println("OK");
        }
}