#include<cstdio>
using namespace std;

int main()
{
    FILE *f=fopen("fact.in","r"),*g=fopen("fact.out","w");
    int x,facto=1,c=0,i,factor;
    bool gasit=false;
    fscanf(f,"%i",&x);
    if(x==0)
        fprintf(g,"1");
    else
        if(x<0)
            fprintf(g,"-1");
        else
            fprintf(g,"%i",x*5);
    fclose(f);
    fclose(g);
    return 0;
}