#include<iostream>
using namespace std;
int main(void) {
	char c;
	int goban[3][3] = { 0 }, result = 0, judge = 0;
	for (int i = 0; i < 3; i++) {
		for (int j = 0; j < 3; j++) {
			cin >> c;
			if (c == '0') return 0;
			if(c=='b')goban[i][j] = 1;
			else if (c == 'w')goban[i][j] = -1;
			else goban[i][j] = 0;
		}
	}
	for (int i = 0; i < 3; i++) {
		for (int j = 0; j < 3; j++) {
			judge += goban[i][j];
		}
		if (judge == 3) result = 1;
		else if (judge == -3) result = -1;

		judge = 0;
	}
	for (int j = 0; j < 3; j++) {
		for (int i = 0; i < 3; i++) {
			judge += goban[i][j];
		}
		if (judge == 3) result = 1;
		else if (judge == -3) result = -1;

		judge = 0;
	}
	for (int i = 0; i < 3; i++) {
			judge += goban[i][i];
		if (judge == 3) result = 1;
		else if (judge == -3) result = -1;

		judge = 0;
	}
	for (int i = 0; i < 3; i++) {
			judge += goban[i][2-i];
		if (judge == 3) result = 1;
		else if (judge == -3) result = -1;

		judge = 0;
	}

	if (result == 1) {
		cout << "b" << endl;
	}
	else if (result == -1) {
		cout << "w" << endl;
	}
	else {
		cout << "NA" << endl;
	}

	return 0;
}