#include <bits/stdc++.h>
using namespace std;
int n, k, t, p, t1, ans;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k;
  t = 240 - k;
  p = 1;
  while (p <= n) {
    t -= 5 * p;
    if (t >= 0) {
      ans++;
    } else {
      break;
    }
    p++;
  }
  cout << ans << "\n";
}
