#include<cstdio>#include<cstring>int T, N, M;int main() {for (scanf ("%d", &T); T--;) {scanf ("%d%d", &N, &M);int dna[1001][4]={}, dic[27]={}, tot=0;dic[0] = 1, dic['C'-'A'] = 2, dic['G'-'A'] = 3, dic['T' - 'A'] = 4;for (int i=0; i<N; i++) {char buf[1024]="";scanf ("%s", buf);for (int j=0; j<M; j++) {dna[j][dic[buf[j]-65]]++;}}for (int i=0; i<M; i++) {int ans = 1, sum = 0;for (int j=1; j<5; j++) {if (dna[i][j] > dna[i][ans]) ans = j;}for (int j=1; j<5; j++) {if (j != ans) sum += dna[i][j];}printf ("%c", ans<2? 'A': ans<3 ? 'C': ans<4 ? 'G': ans<5 ? 'T':0);tot += sum;}printf ("n%dn", tot);}return 0;}
