#include<stdio.h>
long long int p,n,x[14],y[14];
int i;
int main()
{ FILE *f;
f=fopen("fact.in","r");
fscanf(f,"%lld",&p);
fclose(f);
x[0]=1;
for(i=1;i<=13;i++)
{x[i]=5*x[i-1];}
y[0]=0;
for(i=1;i<=13;i++)
{y[i]=5*y[i-1]+1;}
for(i=13;i>=1;i--)
{
n=n+(p/y[i])*x[i];
p=p%y[i];}
f=fopen("fact.out","w");
fprintf(f,"%lld\n",n);
fclose(f);
return 0;
}