#include <bits/stdc++.h>
using namespace std;
#pragma gcc optimize("ofast");
#pragma g++ optimize("ofast");
int n, k, res;
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> k;
  k = 240 - k;
  int i = 1, sum = 0;
  while (i * 5 <= k && i <= n && (sum + i * 5) <= k) sum += i * 5, i++, res++;
  return cout << res << '\n', 0;
}
