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