The first one.

#include <iostream>
#include <string>
using namespace std;
int main(){
    string s1, s2;
    cin >> s1 >> s2;
    int len1 = s1.length();
    int len2 = s2.length();
    if(s1 > s2){
        cout << s2 << " " << s1;
    }else if(s1 == s2){
        cout << s1;
    }else{
        cout << s1 << " " << s2;
    }
    return 0;
}