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<iostream>
#include<string>

using namespace std;

int main()
{
	int k = 0;
	for(;;){
		char MAP[8][8];
		int cont = 0;
		int air_cont = 0;
		bool canCont = false;
		
		for(int i = 0; i < 8; i++){
			for(int j = 0; j < 8; j++){
				cin >> MAP[i][j];
				if(cin.eof()){
					return 0;
				}
			}
		}
		//ツ債カツ端ツづーツ個ゥツづつつッツづつゥツづァツ催古」ツづ個ブツδ債ッツクツつェツ個ゥツづつつゥツづゥツづ慊づづ個凝ウツ板陳青板づーツ記ツ録
		for(int i = 0; i < 8; i++){
			for(int j = 0; j < 8; j++){
				if(MAP[i][j] == '1'){
					cont++;
					if(cont == 1){
						canCont = true;
					}
					if(cont == 4){
						//ツδ仰ーツプツ仰ュツ青ァツ終ツ猟ケ
						goto FIN;
					}
				}
				else if(canCont == true && MAP[i][j] == '0'){
					air_cont++;
				}
			}
		}
		
		FIN:;
		
		switch(air_cont){
			case 0:
				cout << "C" << endl;
				break;
			case 5:
				cout << "G" << endl;
				break;
			case 6:
				cout << "A" << endl;
				break;
			case 7:
				cout << "E" << endl;
				break;
			case 12:
				cout << "D" << endl;
				break;
			case 14:
				cout << "F" << endl;
				break;
			case 21:
				cout << "B" << endl;
				break;
			default:
				cout << "NA" << endl;
		}
	}
}

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

int main(){

  string s[10];

  while(cin >> s[0]){
    for(int i=1;i<8;i++) cin >> s[i];

    for(int i=0;i<8;i++){
      for(int j=0;j<8;j++){
	if(s[i][j] == '1'){

	  if(s[i][j+1] == '1'){
	    if(s[i][j+2] == '1') cout << "C" << endl;
	    else if(s[i+1][j] == '1') cout << "A" << endl;
	    else if(s[i+1][j+1] == '1') cout << "E" << endl;
	    else if(s[i-1][j+1] == '1') cout << "G" << endl;
	  }

	  else if(s[i+1][j] == '1'){
	    if(s[i+2][j+1] == '1') cout << "F" << endl;
	    else if(s[i+1][j-1] == '1') cout << "D" << endl;
	    else if(s[i+3][j] == '1') cout << "B" << endl;
	  }
	  i = 8;
	  j = 8;
	}
      }
    }
  }
}

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

string field[8];

bool ch(int i,int j)
{
	if(field[i][j] == '1') return true;
	return false;
}

bool Check_A(int i,int j)
{
	if(i+1 < 8 && j+1 < 8)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i,j+1) && ch(i+1,j+1))  return true;
	}
	return false;
}

bool Check_B(int i,int j)
{
	if(i+1 < 8 && i+2 < 8 && i+3 < 8)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i+2,j) && ch(i+3,j)) return true;
	}
	return false;
}

bool Check_C(int i,int j)
{
	if(j+1 < 8 && j+2 < 8 && j+3 < 8)
	{
		if(ch(i,j) && ch(i,j+1) && ch(i,j+2) && ch(i,j+3)) return true;
	}
	return false;
}

bool Check_D(int i,int j)
{
	if(j-1 >= 0 && i+1 < 8 && i+2 < 8)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i+1,j-1) && ch(i+2,j-1)) return true;
	}
	return false;
}

bool Check_E(int i,int j)
{
	if(i+1 < 8 && j+1 < 8 && j+2 < 8)
	{
		if(ch(i,j) && ch(i,j+1) && ch(i+1,j+1) && ch(i+1,j+2)) return true;
	}
	return false;
}

bool Check_F(int i,int j)
{
	if(i+1 < 8 && i+2 < 8 && j+1 < 8)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i+1,j+1)&& ch(i+2,j+1)) return true;
	}
	return false;
}

bool Check_G(int i,int j)
{
	if(i+1 < 8 && j+1 < 8 && j-1 >= 0)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i,j+1) && ch(i+1,j-1)) return true;
	}
	return false;
}

int main()
{
	while(cin >> field[0])
	{
		for(int i=1;i<8;i++)
		{
			cin >> field[i];
		}
		
		bool flag = true;
		for(int i=0;i<8;i++)
		{
			for(int j=0;j<8;j++)
			{
				if(Check_A(i,j) && flag)
				{
					cout << "A" << endl;
					flag = false;
				}

				if(Check_B(i,j) && flag)
				{
					cout << "B" << endl;
					flag = false;
				}

				if(Check_C(i,j) && flag)
				{
					cout << "C" << endl;
					flag = false;
				}

				if(Check_D(i,j) && flag)
				{
					cout << "D" << endl;
					flag = false;
				}				

				if(Check_E(i,j) && flag)
				{
					cout << "E" << endl;
					flag = false;
				}

				if(Check_F(i,j) && flag)
				{
					cout << "F" << endl;
					flag = false;
				}

				if(Check_G(i,j) && flag)
				{
					cout << "G" << endl;
					flag = false;
				}
			}
		}
	}
	return 0;
}