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