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 <algorithm>
using namespace std;

/*
0123
456
78
9
*/
const int data[7][10] = {
						{1, 1, 0, 0, 1, 1, 0, 0, 0, 0},
						{1, 0, 0, 0, 1, 0, 0, 1, 0, 1},
						{1, 1, 1, 1, 0, 0, 0, 0, 0, 0},
						{0, 1, 0, 0, 1, 1, 0, 1, 0, 0},
						{1, 1, 0, 0, 0, 1, 1, 0, 0, 0},
						{1, 0, 0, 0, 1, 1, 0, 0, 1, 0},
						{0, 1, 1, 0, 1, 1, 0, 0, 0, 0}
						};

const int change[10][2] = {{0, 0}, {1, 0}, {2, 0}, {3, 0}, {0, 1}, {1, 1}, {2, 1}, {0, 2}, {1, 2}, {0, 3}};

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

	while(1){
		int c[15][15];
		for(int i = 0; i < 15; ++i){
			for(int j = 0; j < 15; ++j){
				c[j][i] = 0;
			}
		}

		for(int i = 0; i < 8; ++i){
			for(int j = 0; j < 8; ++j){
				char c0;
				if(!(cin >> c0)) return 0;
				c[j][i] = c0 - '0';
			}
		}

		//int m = 0;
		bool check2 = false;
		for(int i = 0; i < 8; ++i){
			for(int j = 0; j < 8; ++j){
				for(int k = 0; k < 7; ++k){
					bool check = true;
					for(int l = 0; l < 10; ++l){
						//m = max(m, l);
						if(c[j + change[l][0]][i + change[l][1]] != data[k][l]){
							check = false;
							/*if(i == 4 && j == 4 && k == 1){
								cout << l << endl;
							}*/
							break;
						}
					}
					if(check){
						cout << char('A' + k) << endl;
						check2 = true;
						break;
					}
				}
				if(check2) break;
			}
			if(check2) break;
		}

		//if(!check2) cout << m << endl;
	}

	return 0;
}

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

using namespace std;

typedef struct _XY {
	int x;
	int y;
} XY;

XY figure[][4] = {
	{{1, 0}, {0, 1}, {1, 1}}, // A
	{{0, 1}, {0, 2}, {0, 3}}, // B
	{{1, 0}, {2, 0}, {3, 0}}, // C
	{{0, 1}, {-1, 1}, {-1, 2}}, // D
	{{1, 0}, {1, 1}, {2, 1}}, // E
	{{0, 1}, {1, 1}, {1, 2}}, // F
	{{1, 0}, {0, 1}, {-1, 1}}, // G
};

string name[7] = {"A", "B", "C", "D", "E", "F", "G"};
int main() {
	int math[8][8];
	char c;
	while (1) {
		memset(math, 0, sizeof(math));
		for (int i = 0; i < 8; i++) {
			for (int j = 0; j < 8; j++) {
				c = getchar();
				math[i][j] = c - '0';
			}
			c = getchar();
		}

//		for (int i = 0; i < 8; i++) {
//			for (int j = 0; j < 8; j++) {
//				cout << math[i][j];
//			}
//			cout << endl;
//		}

		XY p;
		for (int i = 0; i < 8; i++) {
			for (int j = 0; j < 8; j++) {
				if (math[i][j] == 1) {
					p.x = j;
					p.y = i;
					goto END;
				}
			}
		}

END:
		for (int i = 0; i < 7; i++) {
			if (math[p.y + figure[i][0].y][p.x + figure[i][0].x] == 1 &&
				math[p.y + figure[i][1].y][p.x + figure[i][1].x] == 1 &&
				math[p.y + figure[i][2].y][p.x + figure[i][2].x] == 1 ) {
				cout << name[i] << endl;
				break;
			}
		}

		c = getchar();
		if (c == EOF)
			break;
	}
	return 0;
}

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

#define SIZE 8

int main() {
	string source[SIZE];
	while (cin >> source[0]) {
		for (int i = 1; i < SIZE; i++) {
			cin >> source[i];
		}

		bool map[14][14] = {false}, f = true;
		int x = SIZE - 1, y = SIZE - 1;
		for (int i = 0; i < SIZE; i++) {
			for (int j = 0; j < SIZE; j++) {
				map[i + 3][j + 3] = (source[i][j] == '1' ? true : false);
				if (source[i][j] == '1' && f) {
					x = j;
					y = i;
				}
			}
		}
		x += 3;
		y += 3;

		if (map[y + 1][x + 1] && map[y][x + 1] && map[y + 1][x]) {
			cout << "A";
		} 
		if (map[y + 1][x + 1] && map[y + 2][x + 1] && map[y + 1][x]) {
			cout << "F";
		}
		if (map[y + 1][x + 1] && map[y + 1][x + 2] && map[y][x + 1]) {
			cout << "E";
		}
		if (map[y - 1][x - 1] && map[y][x + 1] && map[y + 1][x]) {
			cout << "G";
		}
		if (map[y - 1][x - 1] && map[y + 2][x - 1] && map[y + 1][x]) {
			cout << "D";
		}
		if (map[y + 1][x] && map[y + 2][x] && map[y + 3][x]) {
			cout << "B";
		}
		if (map[y][x + 1] && map[y][x + 2] && map[y][x + 3]) {
			cout << "C";
		}
		cout << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
using namespace std;
int main(){
  string str;
  while(cin >> str){
    string st[8];
    st[0]=str;
    int i,j;
    for(i=1;i<8;i++) cin >> st[i];

    //for(i=0;i<8;i++) cout << st[i] << endl;
    //cout << endl;
    char o='0';
    for(i=0;i<8;i++){
      for(j=0;j<8;j++){
	if(st[i][j]=='1'){
	  if(j<7&&i<7){
	    if(st[i][j]=='1'&&
	       st[i+1][j]=='1'&&
	       st[i][j+1]=='1'&&
	       st[i+1][j+1]=='1'){
	      o='A';
	      break;
	    }
	  }
	  if(i<5){
	    if(st[i][j]=='1'&&
	       st[i+1][j]=='1'&&
	       st[i+2][j]=='1'&&
	       st[i+3][j]=='1'){
	      o='B';
	      break;
	    }  
	  }
	  if(j<5){
	    if(st[i][j]=='1'&&
	       st[i][j+1]=='1'&&
	       st[i][j+2]=='1'&&
	       st[i][j+3]=='1'){
	      o='C';
	      break;
	    }
	  }
	  if(0<j&&i<6){
	    if(st[i][j]=='1'&&
	       st[i+1][j]=='1'&&
	       st[i+1][j-1]=='1'&&
	       st[i+2][j-1]=='1'){
	      o='D';
	      break;
	    }
	  }
	  if(j<6&&i<7){
	    if(st[i][j]=='1'&&
	       st[i][j+1]=='1'&&
	       st[i+1][j+1]=='1'&&
	       st[i+1][j+2]=='1'){
	      o='E';
	      break;
	    }
	  }
	  if(j<8&&i<6){
	    if(st[i][j]=='1'&&
	       st[i+1][j]=='1'&&
	       st[i+1][j+1]=='1'&&
	       st[i+2][j+1]=='1'){
	      o='F';
	      break;
	    }
	  
	  }
	  if(j<8&&i<8){
	    if(st[i][j]=='1'&&
	       st[i][j+1]=='1'&&
	       st[i+1][j]=='1'&&
	       st[i+1][j-1]=='1'){
	      o='G';
	      break;
	    }
	  }
	}	
      }
    }
    cout << o << endl;
    //cin >> str;
  }
  return 0;
}