#include <stdio.h>
#include <stdlib.h>

int check(int x,int p)
{
    long long k,ok;
    k=5;
    ok=0;
    while(k<=x)
    {
        ok+=x/k;
        k=k*5;
    }
    if(p==ok)
        return 1;
    else
        return 0;
}
int main()
{
    FILE *fin,*fout;
    fin=("fact.in","r");
    fout=("fact.out","w");
    long long h,x,p;
    int gr;
    fscanf(fin,"%d",&p);
    x=p;
    h=1;
    gr=1;
    if(x>=1)
    {
        while(h*5+1<x)
        {
            h=(h*5)+1;
            gr++;
        }
        while(h!=1)
        {
            x-=(x/h);
            h--;
            h=h/5;
        }
        x=x*5;
        if(check(x,p))
            fprintf(fout,"%d",x);
        else
            fprintf(fout,"-1");
    }
    else if(p==0)
        fprintf(fout,"1");

    fclose(fin);
    fclose(fout);
    return 0;
}