#include<iostream>
using namespace std;
int main(void) {
	while (1) {
		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') break;
				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;
}