#include <bits/stdc++.h>
int main() {
  int n, k, t, c = 0, p = 0;
  scanf("%d %d", &n, &k);
  t = 240 - k;
  for (int i = 1; i <= n; i++) {
    p = p + (5 * i);
    if (p < t)
      c++;
    else if (p == t) {
      c++;
      break;
    } else
      break;
  }
  printf("%d", c);
  return 0;
}
