#include "stdio.h" 

int zero(int n){
    int nr=0;
    while (n>=5)
        nr+=(n/=5);
    return nr;
}

int main() 
{ 
int a,b,c,d; 
FILE *F; 
FILE *G; 
F = fopen("fact.in","r"); 
G = fopen("fact.out","w"); 
    fscanf(F,"%d", &p);
    for (i=0,p2=1<<30;p2>0;p2/=2)
        if (zero(i+p2)<p)
            i+=p2;
    if (zero(i+1)==p)
        fprintf(G,"%d", i+1);
    else
        fprintf(G,"-1");
fprintf(G,"%d",d); 
fclose(G); 
fclose(F); 
return 0; 
}
/*

#include <stdio.h>
 
int zero(int n){
    int nr=0;
    while (n>=5)
        nr+=(n/=5);
    return nr;
}
 
int main()
{
    FILE *fin,*fout;
    int p2,p,i;
    fin=fopen("fact.in","r");
    fout=fopen("fact.out","w");
    fscanf(fin,"%d", &p);
    for (i=0,p2=1<<30;p2>0;p2/=2)
        if (zero(i+p2)<p)
            i+=p2;
    if (zero(i+1)==p)
        fprintf(fout,"%d", i+1);
    else
        fprintf(fout,"-1");
    return 0;
}

*/