#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  int c = 0, b = 1;
  int i;
  for (i = 1; c <= (240 - k); i++) {
    c += (5 * i);
  }
  cout << min(i - 2, n) << endl;
}
