#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k, x, y, count = 0, sum = 0, l;
  cin >> n >> k;
  assert(n <= 10 && k <= 240);
  x = 240 - k;
  l = 10;
  for (int i = 1; i <= n + count; i++) {
    sum += i;
    y = x - (sum * 5);
    if (y < 0) {
      --n;
      count++;
    }
  }
  cout << n;
}
