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++: //A Figure on Surface
#include<bits/stdc++.h>
using namespace std;

string board[8];

inline bool a(int x, int y){return (0<=x && x<8 && 0<=y && y<8);}

int p[7][3][2]={{{0,  1}, {1,  0}, {1,  1}},
                {{1,  0}, {2,  0}, {3,  0}},
                {{0,  1}, {0,  2}, {0,  3}},
                {{1, -1}, {1,  0}, {2, -1}},
                {{0,  1}, {1,  1}, {1,  2}},
                {{1,  0}, {1,  1}, {2,  1}},
                {{0,  1}, {1, -1}, {1,  0}}};

void solve(){
  for(int i=0; i<8; i++){
    for(int j=0; j<8; j++){
      if(board[i][j]=='1'){
        for(int k=0; k<7; k++){
          bool flag=true;
          for(int l=0; l<3; l++){
            if(!a(i+p[k][l][0], j+p[k][l][1]))flag=false;
          }
          if(flag){
            bool flag2=true;
            for(int l=0; l<3; l++){
              if(board[i+p[k][l][0]][j+p[k][l][1]]!='1') flag2=false;
            }
            if(flag2){
              char ans='A'+k;
              cout<<ans<<endl;
              return;
            }
            else continue;
          }
          else continue;
        }
      }
    }
  }
}

int main(){
  while(cin>>board[0]){
    for(int i=1; i<8; i++) cin>>board[i];
    solve();
  }
  return 0;
}

C++: #include <iostream>

using namespace std;

bool input(char b[][8])
{
	char dummy;
	for (int i=0; i<8; i++) {
		for (int j=0; j<8; j++) {
			if ( !(cin >> b[i][j]) ) return false;
		}
		//cin >> dummy;
	}
	return true;
}

int main()
{
	char board[8][8];
	
	while ( input(board) ) {
		pair<int, int> block_pos[4];
		int found_cnt = 0;
		for (int i=0; i<8; i++) {
			for (int j=0; j<8; j++) {
				if (board[i][j] == '1') {
					block_pos[found_cnt].first  = i;
					block_pos[found_cnt].second = j;
					found_cnt++;
					if (found_cnt == 4) break;
				}
			}
		}
		
		if ( block_pos[0].first == block_pos[1].first ) {
			// current candidates : A,C,E,G
			if ( block_pos[0].second == block_pos[2].second ) cout << "A";
			// C,E,G
			else if ( block_pos[1].first == block_pos[2].first ) cout << "C";
			// E,G
			else if ( block_pos[1].second == block_pos[2].second ) cout << "E";
			// G
			else cout << "G";
		}
		// current candidates : B,D,F
		else if (block_pos[0].second != block_pos[1].second) cout << "D";
		else {
			// current candidates : B,F
			if ( block_pos[1].second == block_pos[2].second ) cout << "B";
			// F
			else cout << "F";
		}
		cout << endl;
	}
	
	return 0;
}

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

int main(){
	int mass[8][8];
	
	BEGIN:
	while(scanf("%d%d%d%d%d%d%d%d",(*mass[0]),(*mass[0])+1,(*mass[0])+2,(*mass[0])+3,(*mass[0])+4,
		(*mass[0])+5,(*mass[0])+6,(*mass[0])+7)!=EOF)
	{
		for(int i=1;i<8;i++){
			scanf("%d%d%d%d%d%d%d%d",(*mass[i]),(*mass[i]+1),(*mass[i]+2),(*mass[i]+3),(*mass[i]+4),
				(*mass[i]+5),(*mass[i]+6),(*mass[i]+7));
		}
		for(int i=0;i<8;i++){
			for(int j=0;j<8;j++){
				if(mass[i][j]){
					if(j==7){
						if(mass[i+1][j]){
							cout<<(mass[i+1][j-1]?"D\n":"B\n");
						}
					}else if(j==0){
						if(mass[i][j+1]){
							if(mass[i+1][j]) cout<<"A\n";
							else if(mass[i][j+2]) cout<<"C\n";
							else cout<<"E\n";
						}
						else cout<<(mass[i+1][j+1]?"F\n":"B\n");
					}else{
						if(mass[i][j+2]) cout<<"C\n";
						else if(mass[i][j+1]){
							if(mass[i+1][j]){
								cout<<(mass[i+1][j+1]?"A\n":"G\n");
							}
							else cout<<"E\n";
						}
						else if(mass[i+2][j]) cout<<"B\n";
						else cout<<(mass[i+1][j+1]?"F\n":"D\n");
					}
					goto BEGIN;
				}
			}
		}
	}
	return 0;
}

C++: #include <iostream>
#include <cstring>
using namespace std;
struct P {int x, y; char s[4][5];};
char f[8][9] = {{""}};
bool c(int x, int y, P p)
{
	int i, j;
	char t[8][9];
	for (i = 0; i < 8; i++)
		strcpy(t[i], f[i]);
	for (i = 0; i < p.y; i++)
	{
		for (j = 0; j < p.x; j++)
		{
			t[y+i][x+j] = p.s[i][j];
		}
	}
	for (i = 0; i < 8; i++)
		if (strcmp(t[i], f[i]) != 0)
		{
			return false;
		}
	return true;
}
int main()
{
	P p[7] = {2, 2, {"11", "11"},
		1, 4, {"1", "1", "1", "1"},
		4, 1, {"1111"},
		2, 3, {"01", "11", "10"},
		3, 2, {"110", "011"},
		2, 3, {"10", "11", "01"},
		3, 2, {"011", "110"}};
	int i, j, k;
	bool b;
	char res;
	while (!cin.eof())
	{
		for (i = 0; i < 8; i++)
			cin >> f[i];
		cin.ignore();
		for (i = 0; i < 8; i++)
		{
			for (j = 0; j < 8; j++)
			{
				for (k = 0; k < 7; k++)
				{
					if (8-j >= p[k].x && 8-i >= p[k].y)
						if (b = c(j, i, p[k]))
							res = 'A' + k;
				}
			}
		}
		cout << res << endl;
	}
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <string>

#define rep(x,to) for(int x=0;x<to;x++)
#define rep2(x,from,to) for(int x=from;x<to;x++)

using namespace std;


int main(void){

int cnt=0;
string  w[8], ans;

	while(!cin.eof()){
		ans = "?";
		rep(i,8) rep(j,8) cin >> w[i][j];
		if(cin.eof()) break;
		rep(i,8) rep(j,8) if(w[i][j] == '1'){
			if(w[i][j+1]  + w[i+1][j+1]  + w[i+1][j] == 3 + 3 * '0'){
				ans = "A";  break; }
			if(w[i+1][j]  + w[i+2][j] + w[i+3][j]  == 3 + 3 * '0'){
				ans = "B";  break; }
			if(w[i][j+1]  + w[i][j+2] + w[i][j+3] == 3 + 3 * '0'){
				ans = "C";  break; }
			if(w[i+1][j-1] + w[i+1][j] +  w[i+2][j-1] == 3 + 3 * '0'){
				ans = "D";  break; }
			if(w[i][j+1] + w[i+1][j+1] +  w[i+1][j+2] == 3 + 3 * '0'){
				ans = "E";  break; }
			if(w[i+1][j] + w[i+1][j+1] +  w[i+2][j+1] == 3 + 3 * '0'){
				ans = "F";  break; }
			if(w[i][j+1] + w[i+1][j-1] +  w[i+1][j] == 3 + 3 * '0'){
				ans = "D";  break; }
			}
		cout <<  ans << endl;
//		cnt++; if(cnt>40) break;
	}
	return 0;
	
	
}