#include <bits/stdc++.h>
using namespace std;
const int maxn = 201000;
const int INF = 1000000007;
void solve() {
  int n, k;
  scanf("%d%d", &n, &k);
  int m = 240 - k;
  int ans = 0;
  if (m < 5) {
    printf("0\n");
  } else {
    int x = 1;
    while (1) {
      if (ans >= n) {
        break;
      }
      m -= (x * 5);
      if (m < 0) break;
      ans++;
      x++;
    }
    printf("%d\n", ans);
  }
}
int main() { solve(); }
