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