import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Objects;

public class Main {
    public static void main(String[] args) {
        FastScanner fsc = new FastScanner();
        int n = fsc.nextInt();
        long x = fsc.nextLong();
        long d = fsc.nextLong();
        if (d < 0) {
            x += d * (n - 1);
            d *= -1;
        }
        if (x == 0 || d == 0) {
            if (x == 0 && d == 0) {
                System.out.println(1);
            } else if (x == 0) {
                System.out.println((long) n * (n - 1) / 2 + 1);
            } else {
                System.out.println(n + 1);
            }
            return;
        }
        long gcd = Math.abs(MathUtil.gcd(x, d));
        x /= gcd;
        d /= gcd;
        long ans = 0;
        for (long a = 0; a <= Math.min(d - 1, n); a++) {
            ArrayList<Range> list = new ArrayList<>();
            for (long k = 0; a + k * d <= n; k++) {
                long kd = k * d;
                long kx = k * x;
                long l = kd * (2 * a - 1 + kd) / 2 + kx;
                long r = kd * (2 * (n - a) - 1 - kd) / 2 + kx + a * (n - a);
                list.add(new Range(l, r + 1));
            }
            Collections.sort(list);
            Range now = list.get(0);
            for (Range r : list) {
                if (now.crosses(r)) {
                    now.r = Math.max(now.r, r.r);
                } else {
                    ans += now.length();
                    now = r;
                }
            }
            ans += now.length();
        }
        System.out.println(ans);

    }
}


class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }

    private int readByte() {
        if (hasNextByte()) {
            return buffer[ptr++];
        } else {
            return -1;
        }
    }

    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }

    public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
            ptr++;
        }
        return hasNextByte();
    }

    public String next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }

    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
            throw new NumberFormatException();
        }
        return (int) nl;
    }

    public double nextDouble() {
        return Double.parseDouble(next());
    }
}


class Range implements Comparable<Range> {
    private static final Range EMPTY = new Range(0, 0);

    public long l;
    public long r;

    public Range(long l, long r) {
        this.l = l;
        this.r = r;
    }

    public Range(long r) {
        this(0, r);
    }

    public long length() {
        return r - l;
    }

    public boolean contains(long v) {
        return in(l, v, r);
    }

    public boolean contains(Range r) {
        return contains(this.l, this.r, r.l, r.r);
    }

    public boolean crosses(Range r) {
        return crosses(this.l, this.r, r.l, r.r);
    }

    public Range crossRange(Range r) {
        if (crosses(r)) {
            return new Range(Math.max(this.l, r.l), Math.min(this.r, r.r));
        } else {
            return EMPTY;
        }
    }

    /**
     * judge value is in [l, r).
     * @param l closed.
     * @param value evaluated value.
     * @param r open.
     * @return value is in [l, r)
     */
    public static boolean in(long l, long value, long r) {
        return l <= value && value < r;
    }

    /**
     * judge value is out of [l, r). (i.e. value is in (-infty, l) or [r, infty))
     * @param l closed.
     * @param value evaluated value.
     * @param r open.
     * @return value is out of [l, r) (i.e. value is in (-infty, l) or [r, infty))
     */
    public static boolean outOf(long l, long value, long r) {
        return !in(l, value, r);
    }

    public static boolean crosses(long l1, long r1, long l2, long r2) {
        return l1 < r2 && l2 < r1;
    }

    public static boolean contains(long l1, long r1, long l2, long r2) {
        return l1 <= l2 && r2 <= l1;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        } else if (!(o instanceof Range)) {
            return false;
        } else {
            Range r = (Range) o;
            return this.l == r.l && this.r == r.r;
        }
    }

    @Override
    public int hashCode() {
        return Objects.hash(l, r);
    }

    @Override
    public String toString() {
        return "[" + l + ", " + r + ")";
    }

    @Override
    public int compareTo(Range r) {
        return Long.compare(this.l, r.l);
    }
}


class MathUtil{

    private MathUtil(){}
    
    /**
     * Enumarate primes equal to or less than n.
     * @param n
     * @return {@code ArrayList} that holds primes.
     */
    public static ArrayList<Integer> eratosthenes(int n) {
        int[] div = eratosthenesDivisors(n);
        ArrayList<Integer> result = new ArrayList<>();
        for (int i = 2; i <= n; i++) if (div[i] == i) result.add(i);
        return result;
    }
    /**
     * execute eratosthenes's prime-enumerate algorithm. a[i] holds the greatest
     * divisor of i. if a[i] = i, i is a prime number. This arrary enables you to
     * prime-factorize in O(log n) time.
     * @param n
     * @return divisor array.
     */
    public static int[] eratosthenesDivisors(int n) {
        int[] divisors = new int[n + 1];
        if (n <= 0) return null;
        for (int i = 1; i <= n; i++) {
            if ((i & 1) != 0) divisors[i] = i;
            else divisors[i] = 2;
        }
        for (int i = 3; i <= n; i += 2) {
            if (divisors[i] == i) {
                for (long j = (long) i * i; j <= n; j += i << 1) {
                    divisors[(int) j] = i;
                }
            }
        }
        return divisors;
    }

    /**
     * Caluculate prime-factorization in O(sqrt(n)) time.
     * @param n
     * @return {@code HashMap} of {prime: index}
     */
    public static HashMap<Long, Integer> primeFactorization(long n) {
        HashMap<Long, Integer> primes = new HashMap<>();
        for (long p = 2; p * p <= n; p++) {
            int q = 0;
            while (n % p == 0) {
                n /= p;
                q++;
            }
            if (q > 0) primes.put(p, q);
        }
        if (n > 1) primes.put(n, 1);
        return primes;
    }

    private static HashMap<Long, Integer> lcm(HashMap<Long, Integer> amap, HashMap<Long, Integer> bmap) {
        if (amap.size() < bmap.size()) return lcm(bmap, amap);
        HashMap<Long, Integer> lcm = amap;
        for (Map.Entry<Long, Integer> e : bmap.entrySet()) {
            long prime = e.getKey();
            if (lcm.containsKey(prime)) lcm.put(prime, Math.max(lcm.get(prime), e.getValue()));
            else lcm.put(prime, e.getValue());
        }
        return lcm;
    }
    private static HashMap<Long, Integer> lcm(HashMap<Long, Integer> amap, long b) {
        HashMap<Long, Integer> bmap = primeFactorization(b);
        return lcm(amap, bmap);
    }
    public static HashMap<Long, Integer> lcm(long... a) {
        HashMap<Long, Integer> amap = new HashMap<>();
        for (long c : a) amap = lcm(amap, c);
        return amap;
    }

    /**
     * calculate lcm(a, b) fast. (NOT considering overflow.)
     */
    public static long unsafeLCM(long a, long b) {
        return a * b / gcd(a, b);
    }

    /**
     * Caluculate the GCD of (a, b)/
     * 
     * @param a first value
     * @param b second value
     * @return GCD(a, b)
     */
    public static long gcd(long a, long b) {
        if (a < b) return gcd(b, a);
        if (b == 0) return a;
        if (a == 0) return b;
        long r = a % b;
        while (r != 0) {
            a = b;
            b = r;
            r = a % b;
        }
        return b;
    }
    public static long gcd(long... a){
        long gcd = 0;
        for (long c : a) gcd = gcd(gcd, c);
        return gcd;
    }
    /**
     * Return one of the solutions to {@code ax+by=gcd(a, b)}.
     * @return {@code x}, {@code y}, {@code gcd(a, b)}.
     * @param a a of ax+by=gcd(a, b).
     * @param b b of ax+by=gcd(a, b). class ReferenceLong is a reference type of long.
     */
    public static long[] extGCD(long a, long b) {
        ReferenceLong x = new ReferenceLong();
        ReferenceLong y = new ReferenceLong();
        long[] ret = new long[3];
        ret[2] = extGCD(a, b, x, y);
        ret[0] = x.v;
        ret[1] = y.v;
        return ret;
    }
    private static long extGCD(long a, long b, ReferenceLong x, ReferenceLong y) {
        if (b == 0) {
            x.v = 1;
            y.v = 0;
            return a;
        }
        long d = extGCD(b, a % b, y, x);
        y.v -= a / b * x.v;
        return d;
    }
    private static class ReferenceLong {
        long v = 0;
    }

    public static boolean isPowerOfTwo(long n) {
        return (-n & n) == n;
    }

    public static int ceilExponent(long n) {
        return 63 - Long.numberOfLeadingZeros(n) + (isPowerOfTwo(n) ? 0 : 1);
    }

    public static int floorExponent(long n) {
        return 63 - Long.numberOfLeadingZeros(n) + (n == 0 ? 1 : 0);
    }

    public static int ceilExponent(int n) {
        return 31 - Integer.numberOfLeadingZeros(n) + (isPowerOfTwo(n) ? 0 : 1);
    }

    public static int fllorExponent(int n) {
        return 31 - Integer.numberOfLeadingZeros(n) + (n == 0 ? 1 : 0);
    }
    
    public static int ceilExponent(long n, int base) {
        if (base == 2) {
            return ceilExponent(n);
        }
        int i = 0;
        long m = 1;
        while (m < n) {
            i++;
            long r = m * base;
            if ((m | base) >> 31 != 0 && r / base != m) {
                break;
            }
            m = r;
        }
        return i;
    }
    
    /**
     * caluculate a ^ b NOT considering overflow.
     * so if you want to calculate a ^ b (mod p), use ModUtil.pow(a, b).
     * @param a base
     * @param b exponent
     * @return a ^ b
     */
    public static long pow(int a, int b) {
        if (b == 0) return 1;
        long half = pow(a, b >> 1);
        return half * half * ((b & 1) != 0 ? a : 1);
    }

    /**
     * Caluculate the combination nCr NOT considering overflow.
     * 
     * @param n left
     * @param r right
     * @return nCr
     */
    public static long comb(long n, long r) {
        if (n < r) return 0;
        r = Math.min(r, n - r);
        long res = 1;
        for (long d = 1; d <= r; d++, n--) res *= n / d;
        return res;
    }
}


Measured memory_bytes: 38980