#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, y, a, b, i, c = 0, j = 0;
  cin >> x >> y;
  a = 240 - y;
  for (i = 1; c <= a; i++) {
    c = c + (5 * i);
    j++;
  }
  if (j - 1 <= x) {
    cout << j - 1 << endl;
  } else {
    cout << x << endl;
  }
}
