C :

#include<stdio.h>
int main()
{
	int i,t,k;
	while(scanf("%d",&t)==1)
	{
		i=5;k=0;
		while(t>=i)
		{
			k+=t/i;
			i*=5;
		}
		printf("%d\n",k);
	}
	return 0;
}

C++ :

#include <stdio.h>
int main()
{
	int n;
	while(scanf("%d",&n)!=EOF)
	{
		int sum=0;
		int i=5;
		while(i<=n)
		{
			sum+=n/i;
			i*=5;
		}
		printf("%d\n",sum);
	}
	return 0;
}