Trailing Zeros

1#include<bits/stdc++.h>
2using namespace std;
3#define int long long
4signed main(){
5  ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
6  int n; cin>>n;
7  int ans=0;
8  for(int i=5;i<=n;i*=5)
9    for(int j=i;j<=n;j+=i) ++ans;
10  cout<<ans<<'\n';
11  return 0;
12}