#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 10, size = 1 << 20, mod = 998244353, inf = 2e9;
const long long INF = 1e15;
template <class o>
void qr(o& x) {
  char c = getchar();
  x = 0;
  int f = 1;
  while (!isdigit(c)) {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (isdigit(c)) x = x * 10 + c - '0', c = getchar();
  x *= f;
}
template <class o>
void qw(o x) {
  if (x / 10) qw(x / 10);
  putchar(x % 10 + '0');
}
template <class o>
void pr1(o x) {
  if (x < 0) x = -x, putchar('-');
  qw(x);
  putchar(' ');
}
template <class o>
void pr2(o x) {
  if (x < 0) x = -x, putchar('-');
  qw(x);
  putchar('\n');
}
long long gcd(long long a, long long b) { return !a ? b : gcd(b % a, a); }
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
long long power(long long a, long long b = mod - 2, long long p = mod) {
  long long c = 1;
  while (b) {
    if (b & 1) c = c * a % p;
    b /= 2;
    a = a * a % p;
  }
  return c;
}
template <class o>
void cmax(o& x, o y) {
  if (x < y) x = y;
}
template <class o>
void cmin(o& x, o y) {
  if (x > y) x = y;
}
template <typename t1, typename t2>
void ad(t1& x, t2 y) {
  x += y;
  if (x >= mod) x -= mod;
}
template <typename t1, typename t2>
void dl(t1& x, t2 y) {
  x -= y;
  if (x < 0) x += mod;
}
template <typename T>
struct BIT {
  T* c;
  int n;
  BIT(int _n) : n(_n) {
    c = new T[n];
    c--;
    for (int i = 1; i <= n; i++) c[i] = T(0);
  }
  void add(int x, T y) {
    for (; x <= n; x += x & -x) c[x] = c[x] + y;
  }
  T sum(int x) {
    T y = T(0);
    for (; x; x &= x - 1) y = y + c[x];
    return y;
  }
};
long long jc[N], inv[N];
void jc_init(int n) {
  jc[0] = 1;
  for (int i = 1; i <= n; i++) jc[i] = jc[i - 1] * i % mod;
  inv[n] = power(jc[n]);
  for (int i = n; i; i--) inv[i - 1] = inv[i] * i % mod;
}
long long C(int x, int y) {
  if (x < y || y < 0) return 0;
  return jc[x] * inv[y] % mod * inv[x - y] % mod;
}
int n, m, dif, id[150];
char hy[] = "0AGCT";
string s[N], ans[N], out[N];
void upd(int x) {
  if (x < dif) {
    dif = x;
    for (int i = 0; i <= n - 1; i++) out[i] = ans[i];
  }
}
void solve(int* a) {
  ans[0][0] = a[0];
  ans[0][1] = a[1];
  ans[1][0] = a[2];
  ans[1][1] = a[3];
  int sum = 0;
  for (int i = 0; i <= 1; i++) {
    for (int j = 2; j <= m - 1; j++) ans[i][j] = ans[i][j - 2];
    for (int j = 0; j <= m - 1; j++) sum += ans[i][j] != s[i][j];
  }
  for (int i = 2; i <= n - 1; i++) {
    int u = 0, v = 0;
    for (int j = 0; j <= m - 1; j++) {
      char c = s[i][j];
      u += c != ans[i - 2][j & 1];
      v += c != ans[i - 2][j & 1 ^ 1];
    }
    int o = (u > v);
    for (int j = 0; j <= m - 1; j++) ans[i][j] = ans[i - 2][j & 1 ^ o];
    sum += min(u, v);
  }
  upd(sum);
  sum = 0;
  for (int j = 0; j <= 1; j++) {
    for (int i = 2; i <= n - 1; i++) ans[i][j] = ans[i - 2][j];
    for (int i = 0; i <= n - 1; i++) sum += ans[i][j] != s[i][j];
  }
  for (int j = 2; j <= m - 1; j++) {
    int u = 0, v = 0;
    for (int i = 0; i <= n - 1; i++) {
      char c = s[i][j];
      u += c != ans[i & 1][j - 2];
      v += c != ans[i & 1 ^ 1][j - 2];
    }
    int o = (u > v);
    for (int i = 0; i <= n - 1; i++) ans[i][j] = ans[i & 1 ^ o][j - 2];
    sum += min(u, v);
  }
  upd(sum);
}
void solve() {
  qr(n);
  qr(m);
  dif = inf;
  id['A'] = 1;
  id['G'] = 2;
  id['C'] = 3;
  id['T'] = 4;
  for (int i = 0; i <= n - 1; i++) {
    cin >> s[i];
    for (auto& c : s[i]) c = id[(int)c];
    ans[i].resize(m);
  }
  int a[] = {1, 2, 3, 4};
  do solve(a);
  while (next_permutation(a, a + 4));
  for (int i = 0; i <= n - 1; i++) {
    for (auto& c : out[i]) c = hy[(int)c];
    puts(out[i].c_str());
  }
}
int main() {
  int T = 1;
  while (T--) solve();
  return 0;
}
