#include<bits/stdc++.h>
#define ll long long
#define N 500001
using namespace std;
string s1,s2;
int n,m,a[N],b[N],c[26],lst,flg,cnt,id,typ;
char ans1,ans2,ans3='-';
int main(){
	freopen("troublekey.in","r",stdin);
	freopen("troublekey.out","w",stdout);
	cin>>s1>>s2;
	n=s1.size();
	m=s2.size();
	for(int i=1;i<=max(n,m);i++){
	    if(i<=n) a[i]=s1[i-1]-'a';
	    if(i<=m) b[i]=s2[i-1]-'a';
    }
	for(int i=0;i<26;i++){
		for(int j=0;j<26;j++){
            for(int k=0;k<26;k++) c[k]=0;
			if(i==j) continue;
			lst=cnt=0;
			flg=id=1;
			for(int k=1;k<=n;k++){
				int w=a[k];
				typ=(w==i?1:(w==j?2:0));
				if(typ+lst==3){
					flg=0;
					break;
				}
				if(typ==1){
					if(!c[b[id]]){
						cnt++;
						c[b[id]]++;
					}
					if(cnt>1){
						flg=0;
						break;
					}
					id++;
				}else if(typ==0){
					if(b[id]!=w){
						flg=0;
						break;
					}
					id++;
				}
				lst=typ;
			}
			if(id!=m+1||!flg||!cnt) continue;
			ans1=i+'a';
			for(int k=0;k<26;k++){
			    if(c[k]){
			        ans2=k+'a';
			        break;
                }
            }
			if(n!=m) ans3=j+'a';
			cout<<ans1<<' '<<ans2<<endl<<ans3<<endl;
			return 0;
		}
	}
	return 0;
}