#include <bits/stdc++.h>
using namespace std;
int n1,n2;
string s1,s2;
int i1,i2;
char fal[2],emp;
int main(){
	freopen("troublekey.in","r",stdin);
	freopen("troublekey.out","w",stdout);
	cin>>s1>>s2;
	n1=s1.length();
	n2=s2.length();
	int j1,j2;
	while(i1<n1){
		if(s1[i1]==s2[i2]){
			i1++;i2++;
		}
		else{
			j1=i1;j2=i2;
			while(s1[i1]==s1[j1]) j1++;
			if(s1[j1]==s2[i2]) emp=s1[i1];
			else{
				fal[0]=s1[i1];
				fal[1]=s2[i2];
				j2+=(j1-i1);
			}
			i1=j1;i2=j2;
		}
	}
	printf("%c %c\n",fal[0],fal[1]);
	if(n1==n2) emp='-';
	printf("%c",emp);
	return 0;
}