#include <bits/stdc++.h>
using namespace std;
template <class T>
T sqr(T x) {
  return x * x;
}
template <class T>
T gcd(T a, T b) {
  return (b != 0 ? gcd<T>(b, a % b) : a);
}
template <class T>
T lcm(T a, T b) {
  return (a / gcd<T>(a, b) * b);
}
template <class T>
inline T bigmod(T p, T e, T M) {
  if (e == 0) return 1;
  if (e % 2 == 0) {
    long long int t = bigmod(p, e / 2, M);
    return (T)((t * t) % M);
  }
  return (T)((long long int)bigmod(p, e - 1, M) * (long long int)p) % M;
}
template <class T>
inline T bigexp(T p, T e) {
  if (e == 0) return 1;
  if (e % 2 == 0) {
    long long int t = bigexp(p, e / 2);
    return (T)((t * t));
  }
  return (T)((long long int)bigexp(p, e - 1) * (long long int)p);
}
template <class T>
inline T modinverse(T a, T M) {
  return bigmod(a, M - 2, M);
}
int dx4[] = {1, 0, -1, 0};
int dy4[] = {0, 1, 0, -1};
int dx8[] = {1, 1, 0, -1, -1, -1, 0, 1};
int dy8[] = {0, 1, 1, 1, 0, -1, -1, -1};
int nx8[] = {1, 1, -1, -1, 2, 2, -2, -2};
int ny8[] = {2, -2, 2, -2, 1, -1, 1, -1};
int month[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int a, b, res;
int main() {
  scanf("%d %d", &a, &b);
  if (a > b) swap(a, b);
  int mid = (a + b) / 2;
  int t1 = mid - a;
  int t2 = b - mid;
  res = t1 * (t1 + 1);
  res /= 2;
  t1 = t2 * (t2 + 1);
  t1 /= 2;
  res += t1;
  cout << res;
  return 0;
}
