#include <stdio.h>

using namespace std;
FILE *f,*g;
int fr[22]={0,5,25,125,625,3125,15625,78125,390625,1953125,9765625,48828125,244140725,1220703125};
int main()
{
    f=fopen("factorial.in","r");
    g=fopen("factorial.out","w");
    long long mij,p,s,d,i,zero,nr0=0;
    fscanf(f,"%lld",&p);
    if(p==0)
    {
        fprintf(g,"1");
    }
    else
    {
        s=1,d=p*5;
        while(s<=d)
        {
            mij=(s+d)/2;
            nr0=0;
            for(i=1;fr[i]<=mij;i++)
            {
                nr0+=mij/fr[i];
            }
            if(nr0==p)
            {
                zero=mij;
                d=mij-1;
            }
            else
            {
                if(nr0>p)
                {
                    d=mij-1;
                }
                if(nr0<p)
                {
                    s=mij+1;
                }
            }
        }
        fprintf(g,"%lld",zero);
    }
    fclose(f);
    fclose(g);
    return 0;
}