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)
	}
}

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

int main()
{
    while(true){
        int i=0;
        string map[8];
        while(cin>>map[i],!cin.eof()){
            i++;
            if(i==8){
                break;
            }
        }
        if(cin.eof()){
            break;
        }
        for(int i=0;i<8;i++){
            for(int j=0;j<8;j++){
                if(i<7 && j<7){
                    if(map[i][j]=='1' && map[i][j+1]=='1' && map[i+1][j]=='1' && map[i+1][j+1]=='1'){
                        cout<<'A'<<endl;
                    }
                }
                if(i<5){
                    if(map[i][j]=='1' && map[i+1][j]=='1' && map[i+2][j]=='1' && map[i+3][j]=='1'){
                        cout<<'B'<<endl;
                    }
                }
                if(j<5){
                    if(map[i][j]=='1' && map[i][j+1]=='1' && map[i][j+2]=='1' && map[i][j+3]=='1'){
                        cout<<'C'<<endl;
                    }
                }
                if(j>0 && i<6){
                    if(map[i][j]=='1' && map[i+1][j]=='1' && map[i+1][j-1]=='1' && map[i+2][j-1]=='1'){
                        cout<<'D'<<endl;
                    }
                }
                if(i<7 && j<6){
                    if(map[i][j]=='1' && map[i][j+1]=='1' && map[i+1][j+1]=='1' && map[i+1][j+2]=='1'){
                        cout<<'E'<<endl;
                    }
                }
                if(i<6 && j<7){
                    if(map[i][j]=='1' && map[i+1][j]=='1' && map[i+1][j+1]=='1' && map[i+2][i+1]=='1'){
                        cout<<'F'<<endl;
                    }
                }
                if(i<7 && j>1){
                    if(map[i][j]=='1' && map[i][j-1]=='1' && map[i+1][j-1]=='1' && map[i+1][j-2]=='1'){
                        cout<<'G'<<endl;
                    }
                }
            }
        }
    }
    return 0;
}

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

int main(){

  char str[11][11];

  
  while(scanf("%s",str[0]) != EOF){
    for(int i=1;i<8;i++){
      scanf("%s",str[i]);
    }
    
    for(int i=0;i<8;i++){
      for(int j=0;j<8;j++){
	if(str[i][j]=='1'){
	  if(i<8 && j<8 && str[i][j+1]=='1' && str[i+1][j]=='1' && str[i+1][j+1]=='1'){
	    printf("A\n");
	    goto end;
	  }
	  if(i<6 && str[i+1][j]=='1' && str[i+2][j]=='1' && str[i+3][j]=='1'){
	    printf("B\n");
	    goto end;
	  }
	  if(j<6 && str[i][j+1]=='1' && str[i][j+2]=='1' && str[i][j+3]=='1'){
	    printf("C\n");
	    goto end;
	  }
	  if(i<7 && j>0 && str[i+1][j-1]=='1' && str[i+1][j]=='1' && str[i+2][j-1]=='1'){
	    printf("D\n");
	    goto end;
	  }
	  if(i<8 && j<7 && str[i][j+1]=='1' && str[i+1][j+1]=='1' && str[i+1][j+2]=='1'){
	    printf("E\n");
	    goto end;
	  }
	  if(i<7 && j<8 && str[i+1][j]=='1' && str[i+1][j+1]=='1' && str[i+2][j+1]=='1'){
	    printf("F\n");
	    goto end;
	  }
	  if(i<8 && j<8 && j>0 && str[i][j+1]=='1' && str[i+1][j-1]=='1' && str[i+1][j]=='1'){
	    printf("G\n");
	    goto end;
	  } 
	  
	}
      }
    }
    
  end: int a;
    
  }
  
  return  0;
}

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

#define MAX_LINE 8
#define MAXA_DATA 50

using namespace std;

// プロトタイプ宣言
void searchString(string box);

int main() {
    int i, count = 0;
    int max = MAX_LINE * MAXA_DATA;
    char str[8];
    string box;
    for (i=0; i<max; i++) {
        cin >> str;
        box.append(str);
        //cout << str << endl;
        count++;
        if(count%8 == 0){
            //cout << box << endl << endl;
            // 文字列チェック
            searchString(box);
            box = "";
        }
        /*if((string)str == "finish"){
            break;
        }*/
    }
}

void searchString(string box){
    string A("1100000011");
    string B("1000000010000000100000001");
    string C("1111");
    string D("1000000110000001");
    string E("11000000011");
    string F("100000001100000001");
    string G("110000011");
    if (box.find(A) != std::string::npos) {
        cout << "A" << endl;
    }
    else if(box.find(B) != std::string::npos) {
        cout << "B" << endl;
    }
    else if(box.find(C) != std::string::npos) {
        cout << "C" << endl;
    }
    else if(box.find(D) != std::string::npos) {
        cout << "D" << endl;
    }
    else if(box.find(E) != std::string::npos) {
        cout << "E" << endl;
    }
    else if(box.find(F) != std::string::npos) {
        cout << "F" << endl;
    }
    else if(box.find(G) != std::string::npos) {
        cout << "G" << endl;
    }
}