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