#include <bits/stdc++.h>
using namespace std;
int sum, n, k, a = 5, p;
int main() {
  cin >> n >> k;
  sum = 240 - k;
  p = 5 * n;
  while (sum >= a && a <= p) {
    sum -= a;
    a += 5;
  }
  cout << (a / 5) - 1;
}
