#include <bits/stdc++.h>
using namespace std;
void task_750A() {
  int n, k;
  cin >> n >> k;
  int time = (240 - k) / 5;
  int l = 0, r = time;
  if (time == 1) {
    l = time;
  }
  while (r - l > 1) {
    int m = (l + r) >> 1;
    if ((m * (m + 1) >> 1) <= time) {
      l = m;
    } else {
      r = m;
    }
  }
  cout << min(l, n) << endl;
}
int main() {
  task_750A();
  return 0;
}
