#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a, b;
  cin >> a >> b;
  long long d = abs(a - b);
  long long p1 = (d + 1) / 2, p2 = d / 2;
  long long s1 = (p1 * (p1 + 1)) / 2, s2 = (p2 * (p2 + 1)) / 2;
  cout << s1 + s2;
}
