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