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