include <cmath>

include <cstdio>

include <vector>

include <iostream>

include <algorithm>

using namespace std;

long long check(long long n){
if(n==0) return 0;
long long k=1, m=0;
while(pow(5,k)<=n){
m+=n/pow(5,k);
m%=1000000007;
k++;
k%=1000000007;
}
return k;
}
int main(){
long long n;
cin >> n;
cout << check(n);
}