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 <bits/stdc++.h>
using namespace std;

#define iota(i,n,b,s) for(int i=int(b);i!=int((b)+(s)*(n));i+=(s))
#define range(i,n,m) iota(i,(((n)>(m))?((n)-(m)):((m)-(n))),(n),((n)>(m)?-1:1))
#define rep(i,n) iota(i,(n),0,1)
#define loop for(;;)

#define INF (1e9)
#define EPS (1e-9)
#define cons(a,b) (make_pair(a,b))
#define car(a) (a.first)
#define cdr(a) (a.second)
#define cadr(a) (car(cdr(a)))
#define cddr(a) (cdr(cdr(a)))
#define all(a) a.begin(), a.end()
#define trace(var) cerr<<">>> "<<#var<<" = "<<var<<endl;

typedef long long Integer;
typedef double Real;
typedef vector<int> vi;
typedef vector<string> vs;
typedef map<string,int> Dictionary;
const Real PI = acos(-1);

template<class S, class T>
ostream& operator<<(ostream& os, pair<S,T> p) {
  os << '(' << car(p) << ", " << cdr(p) << ')';
  return os;
}

template<class T>
ostream& operator<<(ostream& os, vector<T> v) {
  if (v.size() == 0) {
    os << "(empty)";
    return os;
  }
  os << v[0];
  for (int i=1, len=v.size(); i<len; ++i) os << ' ' << v[i];
  return os;
}

int dx[] = { -1, 0, 1, 0 };
int dy[] = {  0, -1, 0, 1 };

string fuck(vector<pair<int,int>>&xs) {
  int i0 = INF;
  int j0 = INF;
  int i1 = -INF;
  int j1 = -INF;
  bool zero = false;

  rep (k, 4) {
    int i = car(xs[k]);
    int j = cdr(xs[k]);
    i0 = min(i0, i);
    j0 = min(j0, j);
    i1 = max(i1, i);
    j1 = max(j1, j);
    if (!i && !j) zero = true;
  }

  if (i1 == 3) return "B";
  if (j1 == 3) return "C";
  if (i1 == 1 && j1 == 1) return "A";

  if (i1 == 2) {
    if (zero) return "F";
    return "D";
  }

  if (zero) return "E";
  return "G";
}

int main() {

  loop {
    string ln[8];
    rep (i, 8) cin >> ln[i];

    vector<pair<int,int>> xs;
    int mi = INF;
    int mj = INF;
    rep (i, 8) {
      rep (j, 8) {
        if (ln[i][j] == '1') {
          xs.push_back(cons(i, j));
          mi = min(mi, i);
          mj = min(mj, j);
        }
      }
    }

    rep (i, 4) {
      xs[i] = cons(car(xs[i]) - mi, cdr(xs[i]) - mj);
    }

    cout << fuck(xs) << endl;

    getline(cin, ln[0]);
    if (!cin) break;
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

typedef complex<int> P;

namespace std{
	bool operator < (const P &a,const P &b){
		if( a.real() != b.real() ) return a.real() < b.real();
		return a.imag() < b.imag();
	}
	bool operator == (const P &a,const P &b){
		if( a.real() != b.real() ) return false;
		return a.imag() == b.imag();
	}
};

vector<vector<P>> ptn = {
	{P(0,0),P(1,1),P(1,0),P(0,1)},
	{P(0,0),P(0,2),P(0,1)},
	{P(0,0),P(1,0),P(2,0),P(3,0)},
	{P(1,0),P(1,1),P(0,1),P(0,2)},
	{P(0,0),P(1,0),P(1,1),P(2,1)},
	{P(0,0),P(0,1),P(1,1),P(1,2)},
	{P(1,0),P(2,0),P(0,1),P(1,1)}
};

string s[8];
int main(){
	while(true){
		for(int i = 0 ; i < 8 ; i++){
			if(!(cin >> s[i]))exit(0);
			
		}
		for(int i = 0 ; i < 7 ; i++)
			sort(ptn[i].begin(),ptn[i].end());
		for(int i = 0 ; i < 8 ; i++)
			for(int j = 0 ; j < 8 ; j++){
				vector<P> tmp;
				for(int y = 0 ; y < 8 ; y++)
					for(int x = 0 ; x < 8 ; x++){
						if( s[y][x] == '1'){
							tmp.push_back(P(x-j,y-i));
						}
					}
				sort(tmp.begin(),tmp.end());
				for(int k = 0 ; k < 7 ; k++){
					if( tmp == ptn[k] ){
						cout << (char)(k+'A') << endl;
					}
				}
			}
	}
					
					
	
	
}

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

char c[8][12];

int p;

int find(){
    int i = 0;
    while( c[i/8][i%8] == '0' ) i++;
    return i;
}

bool ex1(int d, int r){
    return c[p/8+d][p%8+r] == '1';
}

int main(){
    char dummy[4];
    while( true ){
        int i = 0;
        while( i < 8 && scanf("%s", c[i]) != EOF ){
            i++;
        }
        if( i < 8 ) break;
        p = find();
        if( ex1(0,1) && ex1(1,0) ){
             if( ex1(1,1) ) puts("A");
             else puts("G");
        }else if( ex1(2,0) ) puts("B");
        else if( ex1(0,2) ) puts("C");
        else if( ex1(1,0) ){
            if( ex1(1,1) ) puts("F");
            else puts("D");
        }else puts("E");
        fgets(dummy, 4, stdin);
    }
    return 0;
}

C++: #include <bits/stdc++.h>  

using namespace std;

#define FOR(i, j, k) for(int i = j; i < k; ++i)
#define rep(i, j) FOR(i, 0, j)
#define repr(i, j) for(int i = j; i >= 0; --i)
#define INF (1 << 30)
#define MOD 1e9 + 7

char s[10][10];

int main() {
	while(cin >> s[0]) {
		FOR(i, 1, 8) cin >> s[i];
		rep(i, 8) rep(j, 8) if(s[i][j] == '1') {
			if(s[i][j+1] == '1') {
				if(s[i+1][j] == '1' && s[i+1][j+1] == '1') {
					printf("A\n");
					goto end;
				}
				else if(s[i+1][j+1] == '1' && s[i+1][j+2] == '1') {
					printf("E\n");
					goto end;
				}
				else if(s[i][j+2] == '1' && s[i][j+3] == '1') {
					printf("C\n");
					goto end;
				}
				else{
					printf("G\n");
					goto end;
				}
			}
			else {
				if(s[i+1][j-1] == '1' && s[i+1][j] == '1' && s[i+2][j-1] == '1') {
					printf("D\n");
					goto end;
				} 
				else if(s[i+1][j] == '1' && s[i+1][j+1] == '1' && s[i+2][j+1] == '1') {
					printf("F\n");
					goto end;
				}
				else {
					printf("B\n");
					goto end;
				}
			}
		}
		end:;
	}
	return 0;
}