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