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