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