#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;
const int INF = INT_MAX;
const long long INFLL = (long long)1e18;
const double PI = acos(-1.0);
template <class T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <class T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
const int N = (int)1e5 + 5;
const int P = 1 << 18;
int a, b;
int main() {
  ios::sync_with_stdio(false);
  cout.setf(ios::fixed | ios::showpoint);
  cout.precision(8);
  cin >> a >> b;
  if (b < a) swap(a, b);
  int ans = INT_MAX;
  for (int i = a; i <= b; i++) {
    int cur;
    cur = ((i - a) * (i - a + 1)) / 2 + ((b - i) * (b - i + 1)) / 2;
    ans = min(ans, cur);
  }
  cout << ans << endl;
  return 0;
}
