#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  int i = 1;
  int total = 240;
  int ans = 0;
  cin >> n >> k;
  total -= k;
  while (total >= 0 && i <= n) {
    total -= 5 * i;
    if (total >= 0) {
      ans++;
    }
    i++;
  }
  cout << ans << endl;
  return 0;
}
