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