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(), "")
		for j := 0; j < 8; j++ {
			ret[i][j], _ = strconv.Atoi(row[j])
		}
	}
	return ret
}

func main() {
	for {
		var board [][]int
		var ans string
		if board = scanBoard(); reflect.DeepEqual(board, [][]int{}) {
			break
		}
		fmt.Println(board)
		for i := 0; i < 8; i++ {
			for j := 0; j < 8; 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 < 8; 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 < 8; 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 < 8; i++ {
			for j := 0; j < 8; 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 < 8; i++ {
			for j := 0; j < 8; 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 < 8; i++ {
			for j := 0; j < 8; 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 < 8; i++ {
			for j := 0; j < 8; 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 <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <cmath>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <iostream>


using namespace std;

int main()
{
	int dx[7][3] = 
	{
		{ 1, 0, 1 },
		{ 0, 0, 0 },
		{ 1, 2, 3 },
		{ -1, 0, -1 },
		{ 1, 1, 2 },
		{ 0, 1, 1 },
		{ 1, -1, 0 }
	};
	int dy[7][3] =
	{
		{ 0, 1, 1 },
		{ 1, 2, 3 },
		{ 0, 0, 0 },
		{ 1, 1, 2 },
		{ 0, 1, 1 },
		{ 1, 1, 2 },
		{ 0, 1, 1 },
	};

	char bb[256];
	char* next = (char*)1;
	while (next)
	{
		char buf[8][8];
		int i;

		for (i = 0; i < 8; ++i)
		{
			if (fgets(bb, 256, stdin) ==NULL)
				break;
			for (int j = 0; j < 8; ++j)
				buf[i][j] = bb[j];
		}
		next = fgets(bb, 256, stdin);
		if (i != 8)
			break;

		int x, y;
		for (y = 0; y < 8; ++y)
		{
			bool found = false;
			for (x = 0; x < 8; ++x)
			{
				if (buf[y][x] == '1')
				{
					found = true;
					break;
				}
			}
			if (found)
				break;
		}

		for (i = 0; i < 7; ++i)
		{
			int j;
			for (j = 0; j < 3; ++j)
			{
				int tx = x+dx[i][j];
				int ty = y+dy[i][j];
				if (tx < 0 || ty < 0 || tx >= 8 || ty >= 8
					|| buf[ty][tx] == '0')
					break;
			}
			if (j == 3)
			{
				printf("%c\n", 'A' + i);
				break;
			}
		}
	}

	return 0;
}

C++: // 2014/09/10 Tazoe

#include <iostream>
using namespace std;

int main()
{
	while(true){
		int Y[4], X[4];
		int I = 0;

		for(int y=0; y<8; y++){
			for(int x=0; x<8; x++){
				char c;
				cin >> c;

				if(cin.eof())
					return 0;

				if(c=='1'){
					Y[I] = y;
					X[I] = x;
					I++;
				}
			}
		}
/*
		for(int i=0; i<4; i++){
			cout << Y[i] << ' ' << X[i] << endl;
		}
*/
		if(Y[1]==Y[0] && Y[2]==Y[0]+1 && Y[3]==Y[0]+1 && X[1]==X[0]+1 && X[2]==X[0] && X[3]==X[0]+1){
			cout << 'A' << endl;
		}
		else if(Y[1]==Y[0]+1 && Y[2]==Y[0]+2 && Y[3]==Y[0]+3 && X[1]==X[0] && X[2]==X[0] && X[3]==X[0]){
			cout << 'B' << endl;
		}
		else if(Y[1]==Y[0] && Y[2]==Y[0] && Y[3]==Y[0] && X[1]==X[0]+1 && X[2]==X[0]+2 && X[3]==X[0]+3){
			cout << 'C' << endl;
		}
		else if(Y[1]==Y[0]+1 && Y[2]==Y[0]+1 && Y[3]==Y[0]+2 && X[1]==X[0]-1 && X[2]==X[0] && X[3]==X[0]-1){
			cout << 'D' << endl;
		}
		else if(Y[1]==Y[0] && Y[2]==Y[0]+1 && Y[3]==Y[0]+1 && X[1]==X[0]+1 && X[2]==X[0]+1 && X[3]==X[0]+2){
			cout << 'E' << endl;
		}
		else if(Y[1]==Y[0]+1 && Y[2]==Y[0]+1 && Y[3]==Y[0]+2 && X[1]==X[0] && X[2]==X[0]+1 && X[3]==X[0]+1){
			cout << 'F' << endl;
		}
		else if(Y[1]==Y[0] && Y[2]==Y[0]+1 && Y[3]==Y[0]+1 && X[1]==X[0]+1 && X[2]==X[0]-1 && X[3]==X[0]){
			cout << 'G' << endl;
		}
	}

	return 0;
}

C++: #include <iostream>
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, 1, 0, 0, 0}
						};

const int change[10][2] = {{0, 0}, {1, 0}, {2, 0}, {3, 0}, {0, 1}, {1, 1}, {2, 1}, {0, 3}, {1, 3}, {0, 4}};

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;
				cin >> c0;
				c[j][i] = (c0 == '0') ? 0 : 1;
			}
		}

		if(cin.eof()){
			break;
		}

		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){
						if(c[j + change[l][0]][i + change[l][1]] != data[k][l]){
							check = false;
							break;
						}
					}
					if(check){
						cout << char('A' + k) << endl;
						check2 = true;
						break;
					}
				}
				if(check2) break;
			}
			if(check2) break;
		}
	}

	return 0;
}

C++: #include <iostream>
#include <vector>
#include <stdio.h>
using namespace std;
int main() {
  char c[11][11];
  vector<int> v;
  int dat[7][6]={{1,1,1,1,0,0},{1,0,1,0,1,0},{1,1,0,0,0,0},{1,0,1,0,0,0},{1,1,0,1,0,0},
  {1,0,1,1,0,1},{1,1,1,0,0,0}};
  int i,j,k,x,y,f;
  while(true) {
      f=0;
	  for (i=0;i<8;i++) {
		  if (gets(c[i])==NULL) { i=10; break;}
		  if (f==0) for (j=0;j<8;j++) if (c[i][j]=='1') { f=1; x=j; y=i; j=9;}
	  }
	  if (i==10) break;
	  cout << endl;
	  for (k=0;k<7;k++) {
		  f=0;
		  for (i=0;i<3;i++) for (j=0;j<2;j++) {
			  if (x+j>7 || y+i>7) f++; else
				  if (c[y+i][x+j]==('0'+dat[k][j+i*2])) f++;
		  }
		  if (f==6) break;
	  }
	  v.push_back(k);
  }
  for (i=0;i<v.size();i++) cout << (char)('A'+v[i]) << endl;
  return 0;
}

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

using namespace std;

int main(void){

	int block[7][3*2]={
		{ 1, 0,  0, 1,  1, 1},
		{ 0, 1,  0, 2,  0, 3},
		{ 1, 0,  2, 0,  3, 0},
		{ 0, 1, -1, 1, -1, 2},
		{ 1, 0,  1, 1,  2, 1},
		{ 0, 1,  1, 1,  1, 2},
		{ 1, 0,  0, 1, -1, 1},
	};
	int field[8][8];
	int ycnt=0,xcnt=0;
	int swit=0,flag;
	int xsta,ysta;
	char inp;

	while(cin>>inp){

		if(inp=='0'){
			field[ycnt][xcnt]=0;
			xcnt++;
		}

		if(inp=='1'){
			field[ycnt][xcnt]=1;
			if(swit==0){
				xsta=xcnt;
				ysta=ycnt;
				swit=1;
			}
			xcnt++;
		}

		if(xcnt==8){
			xcnt=0;
			ycnt++;
		}

		if(ycnt==8){
			xcnt=0;
			ycnt=0;
			swit=0;
			for(int i=0;i<7;i++){
				flag=1;
				for(int j=0;j<6;j+=2){
					if(ysta+block[i][j+1]>=0&&ysta+block[i][j+1]<8&&xsta+block[i][j]>=0&&xsta+block[i][j]<8){
						if(field[ysta+block[i][j+1]][xsta+block[i][j]]!=1){
							flag=0;
						}
					}
					else{
						flag=0;
					}
				}
				if(flag==1){
					cout<<(char)('A'+i)<<endl;
					break;
				}
			}
		}
	}

	return 0;
}

C++: 00000000
00000000
01100000
00110000
00000000
00000000
00000000
00000000

00011110
00000000
00000000
00000000
00000000
00000000
00000000
00000000

00000000
00000000
00110000
00110000
00000000
00000000
00000000
00000000