#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  int l = 240 - k, count = 0;
  for (int i = 1; i <= n; i++) {
    if (l - (5 * i) >= 0) {
      l = l - (5 * i);
      count++;
    }
  }
  cout << count;
  return 0;
}
