#include <bits/stdc++.h>
using namespace std;
int main() {
  double n, m, total = 240;
  cin >> n >> m;
  total -= m;
  total /= 5;
  double x1 = (-1 + sqrt(1 + 4 * 1 * total * 2)) / 2;
  double x2 = (-1 - sqrt(1 + 4 * 1 * total * 2)) / 2;
  x1 = max(x1, x2);
  x1 = min(x1, n);
  x1 = floor(x1);
  cout << x1 << endl;
}
