Shared code

/* 777 */
#include "bits/stdc++.h"
using namespace std;

#define int long long 

// const int MOD=1e9+7;
vector<int>vec;

void solve(){
	int n;cin>>n;
	int cnt=0,div=5;
	while(n/div){
		cnt+=n/div;
		div*=5;
	}
	cout<<cnt<<'\n';
}

signed main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	solve();
}