#include<cstdio>
using namespace std;
int main(){
    int p;
    freopen("factorial.in","r",stdin);
    freopen("factorial.out","w",stdout);
    scanf("%d",&p);
    int i,ci;
    if(p==0){
        printf("1");
        return 0;
    }
    if(p==1){
        printf("5");
        return 0;
    }
    for(i=5;;i=i+5){
        ci=i;
        while((ci/5)%5==0 && ci>0){
            p--;
            ci/=5;
        }
        if(p==0){
            printf("%d",i/5);
            return 0;
        }
        if(p<0){
            printf("-1");
            return 0;
        }
    }
    return 0;
}