#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <cfloat>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <iostream>
#include <memory>
#include <string>

#include <algorithm>
#include <complex>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <bitset>

using namespace std;

#ifdef _MSC_VER
#define __typeof__ decltype
#define strtok_r strtok_s
#endif

#define ITER(c)             __typeof__((c).begin())
#define FOREACH(it, c)      for (ITER(c) it=(c).begin(); it != (c).end(); ++it)
#define RITER(c)            __typeof__((c).rbegin())
#define RFOREACH(it, c)     for (RITER(c) it=(c).rbegin(); it != (c).rend(); ++it)
#define REP(i, n)           REPEAT(i, 0, n)
#define RREP(i, n)          RREPEAT(i, 0, n)
#define REPEAT(i, k, n)     for(int i = (k); i < ((k)+(n)); ++i)
#define RREPEAT(i, k, n)    for(int i = (k)+(n)-1; i >= (k); --i)
#define FROMTO(i,f,t)       for(int i = f; i < t; i++)
#define ALL(c)              (c).begin(), (c).end()
#define LLPOW(p1,p2)        ((ll)pow((double)(p1), (int)p2))
#define ESIZEOF(A)          (sizeof(A)/sizeof((A)[0]))
#define CIN_NO_SYNC         do { cin.tie(0); ios_base::sync_with_stdio(false); } while(0)
#define GETSTR(p)           fgets((p), sizeof(p), stdin)
#define CHOMP(p)            do{ char *_q = (p) + strlen(p)-1; if(*_q == '\n' || *_q == '\r') *_q = 0; } while(0)
#define FILL(m,v)           memset(m, v, sizeof(m))
#define mp                  make_pair
#define pb                  push_back
template<class _T> _T MAX(_T p1,_T p2){return (p1>p2)?p1:p2;} 
template<class _T> _T MIN(_T p1,_T p2){return (p1<p2)?p1:p2;} 
template <class _Tv> inline string join(const _Tv &v,string sep=" "){
    ostringstream s;FOREACH(it,v){if(it!=v.begin())s<<sep;s<<*it;};return s.str();
}

typedef long long ll;
typedef unsigned long long ull;
typedef double D;
typedef complex<D> P;
typedef vector<int> VI;
typedef vector<VI> VVI;
#define X real()
#define Y imag()
#define EPS (1e-9)
#define DEQ(p1,p2) (abs((p1)-(p2)) < EPS)

#ifdef _DEBUG
template<class _Tv> inline void _prfe(const char *_n,const _Tv _c,bool _p=false){
    ITER(_c) _it=_c.begin();
    if(_p){cout<<_n<<" = ["<<endl;for(;_it!=_c.end();++_it)cout<<"    "<<*_it<<endl;cout<<"]"<<endl; }
    else{cout<<_n<<" = [ ";if(_c.size()){cout<<*_it++;for(;_it!=_c.end();++_it)cout<<", "<<*_it;}cout<<" ]"<<endl; }
}
ostream &operator<<(ostream &os, const pair<int,int> &p){return(os<<"("<<p.first<<","<<p.second<<")");}
#define pf printf
#define pr(n) do{cout<<#n" = "<<(n)<<endl;}while(0)
#define prfe(n) _prfe(#n, n)
#define prfep(n) _prfe(#n, n, true)
#define dbgchk(n) do{if(n)throw;}while(0)
#else
#define pf(...) /* */
#define pr(...) /* */
#define prfe(...) /* */
#define prfep(...) /* */
#define dbgchk(...) /* */
#endif


string solve(vector<string> &s){
    REP(i,3){
        int b1 = 0, w1 = 0, b2 = 0, w2 = 0;
        REP(j,3){
            if(s[i][j] == 'b') b1++;
            if(s[i][j] == 'w') w1++;
            if(s[j][i] == 'b') b2++;
            if(s[j][i] == 'w') w2++;
        }
        if(b1 == 3 || b2 == 3) return "b";
        if(w1 == 3 || w2 == 3) return "w";
    }
    int b1 = 0, w1 = 0, b2 = 0, w2 = 0;
    REP(n,3){
        if(s[n][n] == 'b') b1++;
        if(s[n][n] == 'w') w1++;
        if(s[2-n][n] == 'b') b2++;
        if(s[2-n][n] == 'w') w2++;
    }
    if(b1 == 3 || b2 == 3) return "b";
    if(w1 == 3 || w2 == 3) return "w";

    return "NA";
}

int main(){
    vector<string> s(3);
    while(1){
        cin >> s[0] >> s[1] >> s[2];
        if(s[0] == "0") break;
        cout << solve(s) << endl;
    }
    return 0;
}

Measured memory_bytes: 1184