#include<iostream>
#include<string>
#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<cmath>
#include<utility>
#include<set>
#include<complex>
#include<map>
#define vi vector<int>
#define vvi vector<vector<int> >
#define ll long long int
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vb vector<bool>
#define vc vector<char>
#define vs vector<string>
#define ld long double
#define INF 1e9
#define EPS 0.0000000001
#define rep(i,n) for(int i=0;i<n;i++)
#define CC puts("-------ok--------");
#define all(in) in.begin(), in.end()
#define bv vector<bool>
using namespace std;
typedef pair<int, int> pii;
#define MAX 99999999
int main(){
    vector<vector<char>>v(5,vc(5));
    while(cin>>v[0][0]){
        if(v[0][0]=='0')break;
        else for(int i=0; i<3;i++)
            for(int j=0; j<3;j++){
                if((i==0&&j==0))continue;
                    cin>>v[i][j];
            }
    bool flag=false; char ans = '\0';
    rep(i,3)if((v[i][0]==v[i][1])&&(v[i][1]==v[i][2])){
        flag=true;
        ans=v[i][0];
    }rep(i,3){
        if((v[0][i]==v[1][i])&&(v[1][i]==v[2][i])){
            flag=true;
            ans=v[0][i];
        }
    }if((v[0][0]==v[1][1])&&(v[1][1]==v[2][2])){flag=true; ans=v[0][0];}
    if((v[0][2]==v[1][1])&&(v[1][1]==v[2][0])){flag=true; ans=v[1][1];}
    if(flag&&ans!='+')cout<<ans<<endl;
    else cout<<"NA"<<endl;
    }
}