#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 += 5 * i;
    if ((240 - k - sum) >= 0) c++;
  }
  cout << c;
  return 0;
}
