#include <stdio.h>
unsigned long nz(unsigned long n)
{
    unsigned long i,j,k;
    for(i=5,k=0;i<=n;i+=5)
    {
        j=i;
        while(j%5==0)
        {
            j/=5;
            k++;
        }
    }
    return k;
}
unsigned long nrz,nr;
int main()
{
    FILE *f1,*f2;
    f1=fopen("fact.in","r");
    f2=fopen("fact.out","w");
    fscanf(f1,"%lu",&nrz);
    while(nz(nr)<nrz)
        nr+=5;
    fprintf(f2,"%lu",nr);
    return 0;
}