#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <cassert>
#include <iostream>
#include <cctype>
#include <sstream>
#include <string>
#include <list>
#include <vector>
#include <queue>
#include <set>
#include <stack>
#include <map>
#include <utility>
#include <numeric>
#include <algorithm>
#include <iterator>
#include <bitset>
#include <complex>
#include <fstream>
using namespace std;
typedef long long ll;
const double EPS = 1e-9;
typedef vector<int> vint;
typedef pair<int, int> pint;
#define rep(i, n) REP(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define MSG(a) cout << #a << " " << a << endl;
#define REP(i, x, n) for(int i = x; i < n; i++)
template<class T> T RoundOff(T a){ return int(a+.5-(a<0)); }
template<class T, class C> void chmax(T& a, C b){ if(a < b) a = b; }
template<class T, class C> void chmin(T& a, C b){ if(b < a) a = b; }
template<class T, class C> pair<T, C> mp(T a, C b){ return make_pair(a, b); }

string board[3];

bool row(char c)
{
	rep(i, 3) rep(j, 3)
	{
		if(board[i][j] != c) break;
		else if(j == 2) return true;
	}
	
	return false;
}

bool column(char c)
{
	rep(i, 3) rep(j, 3)
	{
		if(board[j][i] != c) break;
		else if(j == 2) return true;
	}
	
	return false;
}

bool diagonal(char c)
{
	rep(i, 3)
	{
		if(board[i][i] != c) break;
		else if(i == 2) return true;
	}
	
	rep(i, 3)
	{
		if(board[2 - i][i] != c) break;
		else if(i == 2) return true;
	}
	
	return false;
}

bool (*pred[3])(char) = {row, column, diagonal};
char ch[2] = {'b', 'w'};

int main()
{
    while(cin >> board[0] && board[0] != "0")
	{
		rep(i, 2) cin >> board[i + 1];
		
		rep(i, 3)
		{
			if(i == 2) cout << "NA" << endl;
			else rep(j, 3) if(pred[j](ch[i]))
			{
				cout << ch[i] << endl;
				goto ng;
			}
		}
		
	ng:;
	}
}