#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, k;
  cin >> n >> k;
  long long int as = 0, ans = 0;
  while (ans <= n) {
    long long int tp = ans * (ans + 1) * 5 / 2;
    if (tp + k <= 240)
      as = ans;
    else
      break;
    ans++;
  }
  cout << as;
  return 0;
}
