#include <algorithm>
#include <iostream>
#include <iomanip>
#include <complex>
#include <cstring>
#include <cstdlib>
#include <string>
#include <vector>
#include <cstdio>
#include <cmath>
#include <map>
#include <set>
using namespace std;
//#pragma comment(linker,"/STACK:102400000,102400000")

int p8[10];
int has[8][1000011];
string s;
char c[1000001];

int MAIN()
{
    p8[0] = 1;
    for(int i = 1; i <= 8; i++)
        p8[i] = p8[i-1] * 8;
    int T;
    scanf("%d", &T);
    
    memset(has, 0, sizeof(has));
    while(T--)
    {
        scanf("%s", c);
        int sLen = strlen(c);

        for(int i = 0; i < sLen; i++)
            for(int j = 1; j <= 7; j++)
                if(i+j-1 < sLen)
                {
                    int v = 0;
                    for(int k = i; k <= i+j-1; k++)
                    {
                        v += (c[k] - 'A') * p8[j-1 -(k-i)];
                    }
                    if(v <= 1000010)
                        has[j][v] ++;
                }
        bool findAns = false;
        for(int i = 1; i <= 7; i++)
        {
            if(findAns)
                break;
            for(int j = 0; j < p8[i]; j++)
                if(has[i][j] == 0)
                {
                    int val = j;
                    string ans;
                    for(int t = 1; t <= i; t++)
                    {
                        ans = char('A' + val % 8) + ans;
                        val = val / 8;
                    }
                    printf("%s\n", ans.c_str());
                    //cout << ans << endl;
                    findAns = true;
                    break;
                }
        }
        for(int i = 0; i < sLen; i++)
            for(int j = 1; j <= 7; j++)
                if(i+j-1 < sLen)
                {
                    int v = 0;
                    for(int k = i; k <= i+j-1; k++)
                    {
                        v += (c[k] - 'A') * p8[j-1 -(k-i)];
                    }
                    if(v <= 1000010)
                        has[j][v] --;
                }
    }    
    return 0;
}

int main()
{
    #ifdef LOCAL_TEST
        freopen("in.txt", "r", stdin);
        freopen("out.txt", "w", stdout);
    #endif
    //ios :: sync_with_stdio(false);
    //cout << fixed << setprecision(16);
    return MAIN();
}