Go: package main

import (
	"bufio"
	"os"
	"strings"
	"strconv"
	"reflect"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

func scanBoard() [][]int {
	ret := make([][]int, 8)
	for k := range ret {
		ret[k] = make([]int, 8)
		for l := range ret[k] {
			ret[k][l] = 0
		}
	}
	for i := 0; i < 8; i++ {
		scanner.Scan()
		row := strings.Split(scanner.Text(), "")
		if reflect.DeepEqual(row, []string{}) {
			break
		}
		for j := 0; j < 8; j++ {
			ret[i][j], _ = strconv.Atoi(row[j])
		}
	}
	return ret
}

func main() {
	for {
		var board [][]int
		var ans string
		if board = scanBoard(); reflect.DeepEqual(board, [][]int{}) {
			break
		}
		fmt.Println(board)
		for i := 0; i < 7; i++ {
			for j := 0; j < 7; j++ {
				if board[i][j] == 1 && board[i+1][j] == 1 && board[i][j+1] == 1 && board[i+1][j+1] == 1 {
					ans = "A"
				}
			}
		}
		for i := 0; i < 5; i++ {
			for j := 0; j < 8; j++ {
				if board[i][j] == 1 && board[i+1][j] == 1 && board[i+2][j] == 1 && board[i+3][j] == 1 {
					ans = "B"
				}
			}
		}
		for i := 0; i < 8; i++ {
			for j := 0; j < 5; j++ {
				if board[i][j] == 1 && board[i][j+1] == 1 && board[i][j+2] == 1 && board[i][j+3] == 1 {
					ans = "C"
				}
			}
		}
		for i := 0; i < 6; i++ {
			for j := 0; j < 7; j++ {
				if board[i][j+1] == 1 && board[i+1][j] == 1 && board[i+1][j+1] == 1 && board[i+2][j] == 1 {
					ans = "D"
				}
			}
		}
		for i := 0; i < 7; i++ {
			for j := 0; j < 6; j++ {
				if board[i][j] == 1 && board[i][j+1] == 1 && board[i+1][j+1] == 1 && board[i+1][j+2] == 1 {
					ans = "E"
				}
			}
		}
		for i := 0; i < 7; i++ {
			for j := 0; j < 6; j++ {
				if board[i][j+1] == 1 && board[i][j+2] == 1 && board[i+1][j] == 1 && board[i+1][j+1] == 1 {
					ans = "G"
				}
			}
		}
		for i := 0; i < 6; i++ {
			for j := 0; j < 7; j++ {
				if board[i][j] == 1 && board[i+1][j] == 1 && board[i+1][j+1] == 1 && board[i+2][j+1] == 1 {
					ans = "F"
				}
			}
		}
		fmt.Println(ans)
	}
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <cmath>

using namespace std;

typedef vector<int> vi;
typedef vector<vi> vii;
typedef vector<string> vs;
typedef vector<bool> vb;
typedef vector<vb> vbb;
typedef pair<int, int> pii;
typedef long long ll;
typedef unsigned long long ull;

#define all(a)  (a).begin(),(a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define pb push_back
#define mp make_pair

#define loop(i,a,b) for(int i=(a);i<ull(b);++i)
#define rep(i,n) loop(i,0,n)

const double eps = 1e-10;
const double pi  = acos(-1.0);
const double inf = (int)1e8;

int main(){
    string field[10];
    while(cin >> field[0]){
        rep(i, 7) cin >> field[i+1];
        rep(i, 10) field[i] += "00000000000000000000000";

        rep(i, 8){
            rep(j, 8){
                if(field[i][j] == '1' && field[i][j+1] == '1' && field[i+1][j] == '1' && field[i+1][j+1] == '1') cout << "A" << endl;
                else if(field[i][j] == '1' && field[i+1][j] == '1' && field[i+2][j] == '1' && field[i+3][j] == '1') cout << "B" << endl;
                else if(field[i][j] == '1' && field[i][j+1] == '1' && field[i][j+2] == '1' && field[i][j+3] == '1') cout << "C" << endl;
                else if(field[i][j+1] == '1' && field[i+1][j+1] == '1' && field[i+1][j] == '1' && field[i+2][j] == '1') cout << "D" << endl;
                else if(field[i][j] == '1' && field[i][j+1] == '1' && field[i+1][j+1] == '1' && field[i+1][j+2] == '1') cout << "E" << endl;
                else if(field[i][j] == '1' && field[i+1][j] == '1' && field[i+1][j+1] == '1' && field[i+2][j+1] == '1') cout << "F" << endl;
                else if(field[i+1][j] == '1' && field[i+1][j+1] == '1' && field[i][j+1] == '1' && field[i][j+2] == '1') cout << "G" << endl;
            }
        }
    }
}

C++: #include <iostream>
#include <string>

using namespace std;

char ret;

int main()
{

	while(cin){
	string s;
	
	for(int i=0;i<8;i++){
		string s_tmp;
		cin >>s_tmp;
		s += s_tmp;
	}
	// 2次元配列を1次元的に処理
	for(int i=0;i<8*8;i++){
		if(s[i]=='1'){
			// Aかどうか
			if(s[i+1]=='1' && s[i+8]=='1' && s[i+9]=='1'){
				ret = 'A';
				break;
			}else if(s[i+8]=='1' && s[i+16]=='1' && s[i+24]=='1'){
				ret = 'B';
				break;
			}else if(s[i+1]=='1' && s[i+2]=='1' && s[i+3]=='1'){
				ret = 'C';
				break;
			}else if(s[i+7]=='1' && s[i+8]=='1' && s[i+15]=='1'){
				ret = 'D';
				break;
			}else if(s[i+1]=='1' && s[i+9]=='1' && s[i+10]=='1'){
				ret = 'E';
				break;
			}else if(s[i+8]=='1' && s[i+9]=='1' && s[i+17]=='1'){
				ret = 'F';
				break;
			}else if(s[i+1]=='1' && s[i+7]=='1' && s[i+8]=='1'){
				ret = 'G';
				break;
			}
		}
	}
	}
	cout<<ret<<endl;
	return 0;
}

C++: /*#include<iostream>
#include<string>
#include<vector>
#include<cstdio>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<map>
#include<functional>
#include<queue>
#include<stack>
#include<set>
using namespace std;
int main(){
int n;
cin>>n;
for(int i=0;i<n;i++){
	double x1,y1,x2,y2,x3,y3,x4,y4;
	bool f=0;
	cin>>x1>>y1>>x2>>y2>>x3>>y3>>x4>>y4;
	double yy1=(y2-y1),yy2=y4-y3;
	if(yy1==0)yy1=0.0000001;
	if(yy2==0)yy2=0.0000001;
	double r1=(x2-x1) / (y2-y1);
	double r2=(x4-x3) / (y4-y3);
	if(abs(r1-r2 ) <=0.000001  )f=1;
	if(f)cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
	}
	return 0;
}*/

/*#include<iostream>
#include<string>
#include<vector>
#include<cstdio>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<map>
#include<functional>
#include<queue>
#include<stack>
#include<set>
using namespace std;
int stoi(string x){stringstream ss;ss<<x;int tmp;ss>>tmp;return tmp;}
string itos(int x){stringstream ss;ss<<x;return ss.str();}
char ta[50][50];
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
char a[]={'R','D','L','U'};
vector<char>ans;
void dfs(int y,int x,char now){
	bool f=1;
	for(int i=0;i<4;i++){
		if(a[i]==now&&ta[y+dy[i]][x+dx[i]]=='1'){
			ans.push_back(a[i]);
			f=1;
			dfs(y+dy[i],x+dx[i],now);
		}
	}
	if(f){
		for(int i=0;i<4;i++){
			if(ta[y+dy[i]][x+dx[i]]=='1'){
				ans.push_back(a[i]);
				dfs(y+dy[i],x+dx[i],a[i]);
			}
		}
	}
}

int main(){


	for(int i=0;i<9;i++){
		for(int j=0;j<4;j++){
			char now;
			cin>>now;
			ta[i][j]=now;
		}
	}
		dfs(0,0,'F');
		for(int i=0;i<ans.size();i++)cout<<ans[i];
		ans.clear();
	return 0;
}*/


#include<iostream>
#include<string>
#include<vector>
#include<cstdio>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<map>
#include<functional>
#include<queue>
#include<stack>
#include<set>
using namespace std;
int stoi(string x){stringstream ss;ss<<x;int tmp;ss>>tmp;return tmp;}
string itos(int x){stringstream ss;ss<<x;return ss.str();}
char ta[12][12];
int main(){
while(cin>>ta[0][0]){
	int y,x;
	bool f=1;
	for(int i=0;i<8;i++){
		for(int j=(i==0);j<8;j++){
			char now;
			cin>>now;
			if(now=='1'&&f){y=i,x=j;f=0;}
			ta[i][j]=now;
		}
	}
	//for(int i=0;i<8;i++){for(int j=0;j<8;j++){cout<<ta[i][j];}cout<<endl;}
	if(ta[y][x+1]=='1'&&ta[y+1][x]=='1'&&ta[y+1][x+1]=='1')cout<<"A";
	
	else if(ta[y+1][x]=='1'&&ta[y+2][x]=='1'&&ta[y+3][x]=='1')cout<<"B";
	
	else if(ta[y][x+1]=='1'&&ta[y][x+2]=='1'&&ta[y][x+3]=='1')cout<<"C";
	
	else if(ta[y][x+1]=='1'&&ta[y+1][x+1]=='1'&&ta[y+1][x+2]=='1')cout<<"E";
	
	else if(ta[y+1][x]=='1'&&ta[y+1][x+1]=='1'&&ta[y+2][x+1]=='1')cout<<"F";
	
	else if(ta[y][x+1]=='1'&&ta[y+1][x]=='1'&&ta[y+1][x-1]=='1')cout<<"G";
	
	else if(ta[y+2][x-1]=='1'&&ta[y+1][x]=='1'&&ta[y+1][x-1]=='1')cout<<"D";

	cout<<endl;
		for(int i=0;i<12;i++)for(int j=0;j<12;j++)ta[i][j]='0';
}
	
	return 0;
}