#include <iostream>

using namespace std;

int count(string s1, string s2){
    int sum = 0;
    for(int i = 0 ; i < s1.length() ; i++){
        if(s1[i] != s2[i])  sum++;
    }
    return sum;
}

void calc_221(string s1, string s2, string s3){
    int l = -1,r = -1;
    for(int i = 0 ; i < s1.length() ; i++){
        if(s1[i] != s2[i]){
            if(l == -1){
                l = i;
            }else{
                r = i;
                break;
            }
        }
    }
    if(s3[l] != s2[l] && s3[l] != s1[l]){
        if(s3[r] == s1[r]){
            s2[r] = s3[r];
            cout<<s2<<endl; return; //DONE!!!
        }else{  //s3[r] == s2[r]
            s1[r] = s3[r];
            cout<<s1<<endl; return; //DONE!!!
        }
    }else{
        if(s3[l] == s1[l]){
            s2[l] = s3[l];
            cout<<s2<<endl; return; //DONE!!!
        }else{  //s2[l] == s1[l]
            s1[l] = s3[l];
            cout<<s1<<endl; return; //DONE!!!
        }
    }
}

void calc_211(string s1, string s2, string s3){
    cout<<s3<<endl; return;
}

void calc_222(string s1, string s2, string s3){
    int count = 0;
    int l = -1;
    for(int i = 0 ; i < s1.length() ; i++){
        if(s1[i] != s2[i] || s2[i] != s3[i] || s1[i] != s3[i]) {
            if(l == -1){
                l = i;
            }
            count++;
        }
    }
    if(count != 3)  {cout<<"Impossible"<<endl;return;}

    if(s1[l] == s2[l])  {s3[l] = s1[l];cout<<s3<<endl;return;}
    if(s3[l] == s2[l])  {s1[l] = s3[l];cout<<s1<<endl;return;}
    if(s1[l] == s3[l])  {s2[l] = s1[l];cout<<s2<<endl;return;}
}


int main(){
    string s1,s2,s3;
    cin>>s1>>s2>>s3;

    int ab,bc,ac;
    ab = count(s1,s2);
    bc = count(s2,s3);
    ac = count(s1,s3);

    // cout<<ab<<" "<<bc<<" "<<ac<<endl;
    if(ab >= 3 || bc >= 3 || ac >= 3)   {cout<<"Impossible"<<endl;return 0;}
    if(ab == 0 || bc == 0 || ac == 0)   {cout<<"Ambiguous"<<endl;return 0;}
    if(ab == 1 && bc == 1 && ac == 1)   {cout<<"Ambiguous"<<endl;return 0;}

    // 2 2 1
    if(ab == 2 && bc == 2 && ac == 1)   {calc_221(s1,s2,s3);return 0;}
    if(ab == 1 && bc == 2 && ac == 2)   {calc_221(s3,s2,s1);return 0;}
    if(ab == 2 && bc == 1 && ac == 2)   {calc_221(s1,s3,s2);return 0;}
    //DONE

    // 2 1 1
    if(ab == 2 && bc == 1 && ac == 1)   {calc_211(s1,s2,s3);return 0;}
    if(ab == 1 && bc == 2 && ac == 1)   {calc_211(s3,s2,s1);return 0;}
    if(ab == 1 && bc == 1 && ac == 2)   {calc_211(s2,s1,s2);return 0;}

    // 2 2 2
    if(ab == 2 && bc == 2 && ac == 2)   {calc_222(s1,s2,s3);return 0;}
    return 0;
}