#include <bits/stdc++.h>
using namespace std;
int n, k, wr, lik, ans;
int main() {
  cin >> n >> k;
  wr = 240 - k;
  lik = 1;
  ans = 0;
  while (true) {
    if (lik * 5 <= wr) {
      wr -= lik * 5;
      lik++;
      ans++;
    } else {
      if (ans > n)
        cout << n;
      else
        cout << ans;
      return 0;
    }
  }
}
