#include<iostream>
#include<vector>
using namespace std;

string s, t;
vector<char> mp;
bool vis[30];
char u, v, ans;

int main(){
	freopen("troublekey.in", "r", stdin);
	freopen("troublekey.out", "w", stdout);
	cin.tie(0) -> ios::sync_with_stdio(0);
	cin >> s >> t;
	if(s.size() == t.size()){
//		int res = 0;
		for(int i = 0;i < s.size();i ++){
			if(s[i] != t[i]){
				u = s[i], v = t[i];
				break;
			}
		}
		cout << u << ' ' << v << '\n';
		cout << '-' << '\n';
		return 0;
	}
	for(int i = 0;i < s.size();i ++){
		if(!vis[s[i] - 'a']){
			mp.push_back(s[i]);
			vis[s[i] - 'a'] = 1;
		}
	}
	for(char x : mp){
		string cnt = "";
		for(int i = 0;i < s.size();i ++){
			if(s[i] != x) cnt += s[i];
		}
//		cout << cnt << '\n';
		if(cnt.size() != t.size()) continue;
		int res = 0;
		for(int i = 0;i < 26;i ++) vis[i] = 0;
		for(int i = 0;i < cnt.size();i ++){
			if(!vis[cnt[i] - 'a'] && cnt[i] != t[i]){
				res ++;
				u = cnt[i], v = t[i];
				vis[cnt[i] - 'a'] = 1;
			}
		}
		if(res == 1){
			cout << u << ' ' << v << '\n';
			cout << x << '\n';
		}
	}
	return 0;
}