#include<iostream>
#include<stdio.h>
#define ui unsigned int
FILE *f=fopen("fact.in","r"),*g=fopen("fact.out","w");
inline ui zer(ui i)
{
    ui t=0;
    while(i) t+=i/=5;
    return t;
}
int main()
{
    ui nr,i,n;
    fscanf(f,"%d",&n);
    for(i=nr=1<<30;nr;nr>>=1)
        i-=i-nr>=1&&zer(i-nr)>=n?nr:0;
    i=zer(i)==n?i:-1;
    fprintf(g,"%d\n",i);
    return 0;
}