#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t;
  int a[10];
  while (~scanf("%d%d", &n, &t)) {
    for (int i = 0; i < 10; i++) a[i] = (i + 1) * 5;
    int temp = 240 - t, sum = 0, j = 0;
    while (temp >= a[j] && j < n) {
      temp -= a[j++];
      sum++;
    }
    cout << sum << endl;
  }
  return 0;
}
