C :

#include <stdio.h>
#include <math.h>

int main()  
{  
	int n; 
    while(scanf("%d",&n)!=EOF)  
    {  
        int sum=0;  
        while(n>=5)  
        {  
            n/=5;
            sum+=n; 
       }  
	   printf("%d\n",sum);  
    }  
    return 0;  
      
}  

C++ :

#include<stdio.h>
int main()
{
	int a=0,b=0,i,j;
	while(~scanf("%d",&a))
	{
		for(i=1 ;i<=a;i++)
		{
			j=i;
			while(j%5==0)
			{
				b++;
				j/=5;
			}

		}
		printf("%d\n",b);
		b=0;
		
	}
	return 0;
}