#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <sstream>
#include <complex>
#include <ctime>
#include <cassert>
#include <functional>

using namespace std;

typedef long long ll;
typedef vector<int> VI;
typedef pair<int,int> PII;

#define REP(i,s,t) for(int i=(s);i<(t);i++)
#define FILL(x,v) memset(x,v,sizeof(x))

int main() {
  int r, c;
  bool shiftleft = true;
  cin >> r >> c;
  REP(i,0,r) {
    string w;
    cin >> w;
    int space = c - w.size();
    if (space % 2) {
      REP(i,0,space / 2) cout << ".";
      if (!shiftleft) cout << ".";
      cout << w;
      REP(i,0,space / 2) cout << ".";
      if (shiftleft) cout << ".";
      cout << endl;
      shiftleft = !shiftleft;
    }
    else {
      REP(i,0,space / 2) cout << ".";
      cout << w;
      REP(i,0,space / 2) cout << ".";
      cout << endl;
    }
  }
  return 0;
}