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