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
}

var emptyBoard = [][]int{{0,0,0,0,0,0,0,0},
						 {0,0,0,0,0,0,0,0},
						 {0,0,0,0,0,0,0,0},
	                     {0,0,0,0,0,0,0,0},
	                     {0,0,0,0,0,0,0,0},
	                     {0,0,0,0,0,0,0,0},
	                     {0,0,0,0,0,0,0,0},
	                     {0,0,0,0,0,0,0,0}}

func main() {
	for {
		var board [][]int
		var ans string
		if board = scanBoard(); reflect.DeepEqual(board, emptyBoard) {
			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)
		fmt.Scanln()
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for(int(i) = 0;(i)<(n);(i)++)
#define pb push_back
#define mp make_pair
#define All(X) X.begin(),X.end()

int main(){
	vector<int> vx, vy;
	while (1){
		vx.clear();
		vy.clear();
		REP(i, 8){
			string str;
			cin >> str;
			
			REP(j, 8){
				if (str[j] == '1'){
					vx.pb(i);
					vy.pb(j);
				}
			}
		}
		char ans = 'G';
		if (vx[0] == vx[1] && vy[0] == vy[2]) ans = 'A';
		if (vy[0] == vy[1] && vy[0] == vy[2] && vy[0] == vy[3]) ans = 'B';
		if (vx[0] == vx[1] && vx[0] == vx[2] && vx[0] == vx[3]) ans = 'C';
		if (vx[1] == vx[2] && vy[1] == vy[3] && vy[0] == vy[2]) ans = 'D';
		if (vx[0] == vx[1] && vx[2] == vx[3] && vy[1] == vy[2] && vy[0] + 2 == vy[3]) ans = 'E';
		if (vx[1] == vx[2] && vy[0] == vy[1] && vy[2] == vy[3]) ans = 'F';
		
		cout << ans << endl;
		if (cin.eof()){
			return 0;
		}
	}
}

C++: #include<cstdio>
#include<cstring>

int main(){
	char p[7][19] = {"1100000011", "10000000100000001", "1111", "1000000110000001", "11000000011", "100000001100000001", "110000011"};
	char f[65];
	char t;
	while(1 + scanf("%c", &t)){
		while(t == 10){
			scanf("%c", &t);
		}
		f[0] = t;
		for(int i = 1; i < 64; i++){
			scanf("%c", &t);
			while(t == 10){
				scanf("%c", &t);
			}
			f[i] = t;
		}
		f[64] = '\0';
		for(int i = 0; i < 7; i++){
			if(strstr(f, p[i])){
				printf("%c\n", i + 'A');
			}
		}
		scanf("%c", &t);
	}
	return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <string>
#include <math.h>
#include <algorithm>
#include <vector>
#include <map>
#include <cstdio>
#include <utility>

using namespace std;
typedef pair<double,double> P;




int main(){
	int field[8][8];
	string field1[8];
	
	while(cin >> field1[0]){
		for(int i = 1;i < 8;i++){
			cin >> field1[i];
		}
		for(int i = 0;i < 8;i++){
			for(int j = 0;j < 8;j++){
				if(field1[i][j] == '1') field[i][j] = 1;
				else field[i][j] = 0;
			}
		}
		/*for(int i = 0;i < 8;i++){
			for(int j = 0;j < 8;j++){
				cout << field[i][j];
			}
			cout << endl;
		}
		cout << endl;*/
		for(int i = 0;i < 8;i++){
			int flag = 0;
			for(int j = 0;j < 8;j++){
				if(field[i][j] == 1){
					//cout << i << j <<endl;
					if(field[i][j+1] == 1){
						if(field[i+1][j] == 1){
							if(field[i+1][j+1] == 1){
								cout << "A" << endl;
								flag = 1;break;
							}
							else if(field[i+1][j-1] == 1){
								cout << "G" << endl;
								flag = 1;break;
							}
						}
						else if(field[i][j+2] == 1 && field[i][j+3] == 1){
							cout << "C" << endl;
							flag = 1;break;
						}
						else if(field[i+1][j+1] == 1 && field[i+1][j+2] == 1){
							cout << "E" << endl;
							flag = 1;break;
						}
					}
					else if(field[i+1][j] == 1){
						if(field[i+1][j-1] == 1 && field[i+2][j-1] == 1){
							cout << "D" << endl;
							flag = 1;break;
						}
						else if(field[i+1][j+1] == 1 && field[i+2][j+1] == 1){
							cout << "F" << endl;
							flag = 1;break;
						}
					}
					else if(field[i+1][j] == 1 && field[i+2][j] == 1 && field[i+3][j] == 1){
						cout << "B" << endl;
						flag = 1;break;
					}
				}
			}
			if(flag == 1) break;
		}
	}

	return 0;
}

C++: #include <vector>
#include <iostream>
#include <utility>
#include <algorithm>
#include <string>
#include <deque>
#include <queue>
#include <tuple>
#include <queue>
#include <functional>
#include <cmath>
#include <iomanip>
#include <map>
#include <set>
#include <numeric>
#include <unordered_map>
#include <unordered_set>
#include <complex>
#include <iterator>
#include <array>
#include <memory>
#include <stack>
#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 loop(i,s,n) for(int i=s;i<n;i++)
#define all(in) in.begin(), in.end()
template<class T, class S> void cmin(T &a, const S &b) { if (a > b)a = b; }
template<class T, class S> void cmax(T &a, const S &b) { if (a < b)a = b; }
#define MAX 9999999
using namespace std;
typedef pair<int, int> pii;
typedef pair<double,double>pdd;
typedef pair<ll,ll>pll;
int main(){
    char tiya[8][8];
    while(true){
    if(cin.eof())break;
        cin>>tiya[0][0];
        if(tiya[0][0]=='\0')cin>>tiya[0][0];
    vector<pii>gotiusa;
    rep(i,8)rep(j,8){
        if(i==0&&j==0)continue;
        cin>>tiya[i][j];
        if(tiya[i][j]=='1')gotiusa.push_back(pii(i,j));
    }
    int tate=0;
    int yoko=0;
    pii t=pii(-INF,INF),y=pii(-INF,INF);
    rep(i,gotiusa.size()){
        cmax(t.first,gotiusa[i].first);
        cmin(t.second,gotiusa[i].first);
        cmax(y.first,gotiusa[i].second);
        cmin(y.second,gotiusa[i].second);
    }
    tate=t.first-t.second;
    yoko=y.first-y.second;
    if(tate==3) puts("B");
    else if(yoko==3) puts("C");
    else if(yoko==1&&tate==1)puts("A");
    else if(tate==2&&yoko==1){
        int a = 0,b = 0;
        rep(i,gotiusa.size()){
            if(t.first==gotiusa[i].first)a=gotiusa[i].second;
            else if(t.second==gotiusa[i].first)b=gotiusa[i].second;
        }
            (a>b ? puts("D"):puts("F"));
    }
    else if(tate==1&&yoko==2){
        int a = 0,b = 0;
        rep(i,gotiusa.size()){
            if(y.first==gotiusa[i].second)a=gotiusa[i].first;
            else if(y.second==gotiusa[i].second)b=gotiusa[i].first;
        }
            (a>b ? puts("E"):puts("G"));
        }
    }
    return 0;
}