洛谷 B2029 大象喝水

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const double pi = 3.14;
int main() {
	LL h, r;
	cin >> h >> r;
	double V;
	V = pi * r * r * h;
	cout << ceil(20 * 1000 / V) << endl;
	return 0;
}