#include <stdio.h>

int r1(int n)
{
	if (n<10)
		return n;
	return r1(n/10);
}

int r2(int n){
	if (n%2==0)
		return n%10;
	else
		if (n<10)
			return -1;
		else
			return r2(n/10);
}
int r3(int n){
	if (n<10){
		if (n%2==0)
			return n;
		else
			return -1;
	} else{
		int res=r3(n/10);
		if (res==-1 && n%2==0)
			return n%10;
		else
			return res;
	}
}
int r4(int n){
	if (n<10)
		return n;
	int res=r4(n/10);
	if (n%10==0)
		return res;
	else
		return res*10+n%10;
}

int main(){
	int n;
	freopen("test.in","r",stdin);
	freopen("test.out","w",stdout);
	scanf("%d",&n);
	printf("%d\n%d\n%d\n%d\n",r1(n),r2(n),r3(n),r4(n));
	return 0;
}