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