#include <bits/stdc++.h>
using namespace std;
long long n, m;
long long MAX = 1000000009;
int main() {
  cin >> n >> m;
  int tot = 240, cnt = 0, time = 0;
  for (int i = 1; i <= n; i++) {
    time += (5 * i);
    if (time + m > tot) {
      break;
    } else {
      cnt++;
    }
  }
  cout << cnt << endl;
  return 0;
}
