#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, k, sum, res, c;
  cin >> n >> k;
  res = 240 - k, sum = 0, c = 0;
  for (int i = 1; i <= n; i++) {
    sum += 5 * i;
    if (sum > res) break;
    c = c + 1;
  }
  cout << c << "\n";
}
