#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  while (cin >> n >> k) {
    int d = 240 - k;
    int cnt = 0;
    int p = 5;
    int b = 5;
    while (p <= d) {
      b += 5;
      p += b;
      cnt++;
    }
    printf("%d\n", min(cnt, n));
  }
  return 0;
}
