#include<stdio.h>
FILE *in,*out;
int nr0,p;
int num,aux,aux2;

inline int verif()
{
    if(p<=0)
        return -1;
    while(nr0<p)
    {
        num+=25;
        nr0+=4;
        aux=num;
        if(nr0<p)
        {
            while( !(aux%5) )
            {
				nr0++;
				aux/=5;
			}
		}
		else
		{
			aux2=nr0-p+1;
			num-=5*aux2;
			nr0-=aux2-1;
		}
    }
    if(nr0==p)
        return num;
    else
        return -1;

}

int main()
{
	in=fopen("fact.in","rt");
	out=fopen("fact.out","wt");
	fscanf(in,"%d",&p);
	fprintf(out,"%d",verif());
	return 0;
}