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 <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <complex>
#include <ctime>
#include <cstdlib>

using namespace std;

inline int to_int(string s) {int v; istringstream sin(s); sin >> v; return v;}
template<class T> inline string to_str(T x) {ostringstream sout; sout << x; return sout.str();}

typedef long long ll;

int main()
{
	char ans = '0', wk;
	int F[16][16];
	while(cin >> wk)
	{
		memset(F, 0, sizeof(F));
		if(wk == '\n')
		{
			continue;
		}
		F[0][0] = wk - '0';
		ans = '0';


		for(int i = 0; i < 8; i++)
		{
			for(int j = 0; j < 8; j++)
			{
				if(i == 0 && j == 0)
					continue;
				cin >> wk;
				F[i][j] = wk - '0';
			}
		}

		for(int i = 0; i < 8; i++)
		{
			for(int j = 0; j < 8; j++)
			{
				if(F[i][j] && F[i][j+1] && F[i+1][j] && F[i+1][j+1])
				{
					ans = 'A';
					break;
				}
				if(F[i][j] && F[i+1][j] && F[i+2][j] && F[i+3][j])
				{
					ans = 'B';
					break;
				}
				if(F[i][j] && F[i][j+1] && F[i][j+2] && F[i][j+3])
				{
					ans = 'C';
					break;
				}
				if(F[i][j] && F[i+1][j] && F[i+1][j-1] && F[i+2][j-1])
				{
					ans = 'D';
					break;
				}
				if(F[i][j] && F[i][j+1] && F[i+1][j+1] && F[i+1][j+2])
				{
					ans = 'E';
					break;
				}
				if(F[i][j] && F[i+1][j] && F[i+1][j+1] && F[i+2][j+1])
				{
					ans = 'F';
					break;
				}
				if(F[i][j] && F[i][j+1] && F[i-1][j+1] && F[i-1][j+2])
				{
					ans = 'G';
					break;
				}
			}
			if(ans != '0')
			{
				break;
			}
		}

		cout << ans << endl;
	}
}

C++: #include <iostream>
using namespace std;

int main()
{
     int num[8];
     int pattan[7][4] = {{11000000, 11000000, 0, 0},
                         {10000000, 10000000, 10000000, 10000000},
                         {11110000, 0, 0, 0},
                         {1000000, 11000000, 10000000, 0},
                         {11000000, 1100000, 0, 0},
                         {10000000, 11000000, 1000000, 0},
                         {1100000, 11000000, 0, 0} };
     while (cin >> num[0]) {
          for (int i = 1; i < 8; i++) cin >> num[i];
          int t = 0;
          while (num[t] == 0) t++;
          //char
          for (int i = 0; i < 7; i++) {
               //sift
               for (int j = 0; j < 8;j++) {
                    //good mach
                    int flag = 1, tmp = 1;
                    for (int k = 0; k < j; k++) tmp *= 10;
                    for (int k = 0; k < 4; k++)
                         if (num[t + k] != (pattan[i][k] / tmp) && t + k < 8) flag = 0;
                    char str = 'A' + i;
                    if (flag) cout << str << endl;
               }
          }
     }

     return 0;
}

C++: #include<iostream>
using namespace std;
int main() {
	while (cin){
		char c[8][8];
		for (int i = 0; i < 8; i++)
			for (int j = 0; j < 8; j++)
				cin >> c[i][j];
		int a, b;
		for (int i = 0; i < 8; i++) {
			for (int j = 0; j < 8; j++) {
				if (c[i][j] == '1') {
					a = i;
					b = j;
					goto C;
				}
			}
		}
	C:
		if (c[a][b + 1] == '1') {
			if (c[a + 1][b] == '1') {
				if (c[a + 1][b + 1] == '1')
					cout << 'A';
				else cout << 'G';
			}
			else {
				if (c[a + 1][b + 1] == '1')
					cout << 'E';
				else cout << 'C';
			}
		}
		else if (c[a + 1][b + 1] == '1')
			cout << 'F';
		else if (c[a + 1][b - 1] == '1')
			cout << 'D';
		else cout << 'B';
		cout << endl;
	}
	return 0;
}

C++: #include<iostream>
using namespace std;
int main() {
	char c[10][10];
    while (cin>>c[0][0]){
        for (int i = 0; i < 8; i++)
            for (int j = 0; j < 8; j++)
                if(!i&&!j)continue;
                cin >> c[i][j];
        int a, b;
        for (int i = 0; i < 8; i++) {
            for (int j = 0; j < 8; j++) {
                if (c[i][j] == '1') {
                    a = i;
                    b = j;
                    goto C;
                }
            }
        }
    C:
        if (c[a][b + 1] == '1') {
            if (c[a + 1][b] == '1') {
                if (c[a + 1][b + 1] == '1')
                    cout << 'A';
                else cout << 'G';
            }
            else {
                if (c[a + 1][b + 1] == '1')
                    cout << 'E';
                else cout << 'C';
            }
        }
        else if (c[a + 1][b + 1] == '1')
            cout << 'F';
        else if (c[a + 1][b - 1] == '1')
            cout << 'D';
        else cout << 'B';
        cout << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<string>
using namespace std;

int main(){
	string line[8];

	while(true){


		int w = 0, h = 0, t=-1;

		for(int i=0;i<8;++i)
			cin >> line[i];

		int right=0,left=7;

		for(int i=0;i<8;++i){
			bool exist = false;
			for(int j=0;j<8;++j){
				if((line[i])[j] == '1'){
					if(t!=-1)t=i;
					if(j>right)right = j;
					if(j<left)left = j;
					exist = true;
				}
			}
			if(exist)++h;
		}
		w = right - left + 1;

		if( w == 2 && h == 2 )cout<<"A"<<endl;
		else if(w == 1)cout<<"B"<<endl;
		else if(h == 1)cout<<"C"<<endl;


		else if(w==2){
			for(int i=0;i<8;++i){
				if((line[i])[left] == '1'){
					if((line[i])[left+1]=='1')
						cout<<"D"<<endl;
					else
						cout<<"F"<<endl;
					break;
				}
			}
		}

		else if(h==2){
			for(int i=0;i<8;++i){
				if((line[t])[i]=='1'){
					if((line[t+1])[i]=='1')
						cout<<"G"<<endl;
					else
						cout<<"E"<<endl;
				}
			}
		}
		else
		{}

	}
	return 0;
}