#include <bits/stdc++.h>
using namespace std;
int main()
{
long int n;
while(cin >> n)
cout<< n/5+n/25+n/125+n/625+n/3125+n/15625+n/78125+n/390625+n/1953125+n/9765625+n/48828125+n/244140625+n/1220703125;
cout<<endl;
}
這有點東西
行!