#include <bits/stdc++.h>
int main() {
  int n, k;
  while (~scanf("%d %d", &n, &k)) {
    int x = 240 - k, sum = 0, ans = 0;
    for (int i = 1; i <= n; i++) {
      sum += 5 * i;
      if (sum > x) break;
      ans++;
    }
    printf("%d\n", ans);
  }
}
