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