#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a, b, c, d, i, j, n, k, sum;
  while (cin >> n >> k) {
    sum = 0, d = 0;
    if (k >= 240) {
      cout << "0" << endl;
    } else {
      for (i = 1; i <= n; i++) {
        sum = sum + (i * 5);
        c = sum + k;
        if (c > 240) break;
        d++;
      }
      cout << d << endl;
    }
  }
}
