#include <cstdio>#include <cstring>#include <cstdlib>#include <iostream>#include <algorithm>#include <cmath>#include <set>#include <queue>#include <stack>#include <map>#include <vector>using namespace std;typedef long long ll;typedef unsigned long long ull;typedef pair<int, int> P;const int maxn = 20;char a[55][1010];char b[1010];const char ch[] = {‘A‘, ‘C‘, ‘G‘, ‘T‘};int main(){    //freopen("in.txt", "r", stdin);    //freopen("out.txt", "w", stdout);    int T;    scanf("%d", &T);    while(T--)    {        int ans = 0;        int m, n;        scanf("%d%d", &m, &n);        for(int i = 0; i < m; i++)            scanf("%s", a[i]);        int cnt[4];        for(int i = 0; i < n; i++)        {            memset(cnt, 0, sizeof(cnt));            for(int j = 0; j < m; j++)            {                int k = 0;                while(ch[k] != a[j][i])                    k++;                cnt[k]++;            }            int maxnum = 0;            for(int j = 0; j < 4; j++)                if(cnt[j] > maxnum)                    maxnum = cnt[j];            for(int j = 0; j < 4; j++)            {                if(cnt[j] == maxnum)                {                    b[i] = ch[j];                    ans += m - maxnum;                    break;                }            }        }        b[n] = ‘\0‘;        printf("%s\n", b);        printf("%d\n", ans);    }    return 0;}