#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, k;
  cin >> n >> k;
  int minSpend = k;
  int pSolved = 0;
  for (int i = 1; i <= n; i++) {
    minSpend = minSpend + (i * 5);
    if (minSpend <= 240) {
      pSolved++;
    }
  }
  cout << pSolved;
  return 0;
}
