纯代码

#include <bits/stdc++.h> 
using namespace std;
int main(){
    int h,r;    
    cin >> h >> r;
    double PI = 3.14159;
    double V = PI * r * r * h;
    int sum = ceil(20000 / V);
    cout << sum;
    return 0;
}

拜拜~