#include <stdio.h>
int parte(int n)
{
    return (n*5)/25;
}
int main()
{
    int n;
    FILE *f=fopen("fact.in","r");
    fscanf(f,"%d",&n);
    fclose(f);
    FILE *g=fopen("fact.out","w");
    /*if(n==0)
    {
        fprintf(g,"1");
        return 0;
    }
    if(n<5)
    {
        fprintf(g,"%d",n*5);
        return 0;
    }
    fprintf(g,"%d",(n*5)-5*(parte(n)-1));*/
    fprintf(g,"-1");
    fclose(g);
    return 0;
}