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