#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x;
  while (cin >> n >> x) {
    if (n == 0 && x == 0) break;
    int cnt = 0;
    for (int i = 1; i <= n; i++)
      for (int j = i + 1; j <= n; j++)
        for (int k = j + 1; k <= n; k++) {
          if (i + j + k == x) ++cnt;
        }
    cout << cnt << endl;
  }
  return 0;
}