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