#include <bits/stdc++.h>
using namespace std;
string itos(int x) {
  stringstream ss;
  ss << x;
  return ss.str();
}
int n, k, res, now = 5;
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n >> k;
  k = 240 - k;
  while (k >= now) {
    k -= now;
    now += 5;
    res++;
  }
  cout << min(n, res) << endl;
  return 0;
}
