#define _USE_MATH_DEFINES
#include <iostream>
#include <complex>
#include <algorithm>
#include <vector>
#include <stack>
#include <string>
#include <queue>
#include <cmath>
#include <math.h>
#include <numeric>
#include <list>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <climits>
#include <set>
#include <memory.h>
#include <memory>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cassert>
#include <map>
#include <cassert>
#include <time.h>
#include <ctime>

using namespace std;

typedef complex<double> xy_t;
typedef pair<xy_t, xy_t> line;
typedef long long ll;
typedef pair<int, int> P;
typedef pair<int , P> PP;
typedef pair<int, string> Ps;
typedef vector<int> vec;
typedef vector<vec> mat;
const int INF = 1 << 30;
const double EPS = 1e-9;
const double PI = 3.1415926535897932384626433832795;
const int CLK = CLOCKS_PER_SEC;

#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, m, n) for(int i = m; i < n; i++)

char field[9];

bool ok(char c){
	bool res = false;
	bool f;
	rep(i, 3){
		f = true;
		rep(j, 3) if(field[i*3+j]!=c) f = false;
		if(f) res = true;
	}
	rep(i, 3){
		f = true;
		rep(j, 3) if(field[i+j*3]!=c) f = false;
		if(f) res = true;
	}
	if(field[0] == c && field[4] == c && field[8] == c) res = true;
	if(field[2] == c && field[4] == c && field[6] == c) res = true;
	return res;

}

int main(){
	while(cin >> field[0] && field[0] != '0'){
		rep2(i, 1, 9) cin >> field[i];
		bool b = ok('b');
		bool w = ok('w');
		if(b) cout << 'b' << endl;
		else if(w) cout << 'w' << endl;
		else cout << "NA" << endl;
	}
	return 0;
}