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