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>
#include <cmath>
#include <cstdio>
#include <string>
#include <map>
#include <vector>
#include <stack>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)

string mass[8];

char solve(int i, int j)
{
    if (mass[i][j] == '1' && mass[i][j+1] == '1' && mass[i+1][j] == '1' && mass[i+1][j+1] == '1') {
        return 'A';
    }
    else if (mass[i][j] == '1' && mass[i+1][j] == '1' && mass[i+2][j] == '1' && mass[i+3][j] == '1') {
        return 'B';
    }
    else if (mass[i][j] == '1' && mass[i][j+1] == '1' && mass[i][j+2] == '1' && mass[i][j+3] == '1') {
        return 'C';
    }
    else if (mass[i][j] == '1' && mass[i+1][j] == '1' && mass[i+1][j-1] == '1' && mass[i+2][j-1] == '1') {
        return 'D';
    }
    else if (mass[i][j] == '1' && mass[i][j+1] == '1' && mass[i+1][j+1] == '1' && mass[i+1][j+2] == '1') {
        return 'E';
    }
    else if (mass[i][j] == '1' && mass[i+1][j] == '1' && mass[i+1][j+1] == '1' && mass[i+2][j+1] == '1') {
        return 'F';
    }
    else if (mass[i][j] == '1' && mass[i][j+1] == '1' && mass[i-1][j] == '1' && mass[i-1][j-1] == '1') {
        return 'G';
    }
    
    return 0;
}

int main(void)
{
    char c;
    bool f;
    
    while (!cin.eof()) {
        f = false;

        for (int i = 0; i < 8; i++) {
            cin >> mass[i];
        }
        
        rep(i, 8) {
            rep(j, 8) {
                if (mass[i][j] == '1' && f == false) {
                    c = solve(i, j);
                    cout << c << endl;
                    f = true;
                }
            }
        }
    }
    
    return 0;
}

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

const double EPS = 1.0e-6;

int main()
{
	while(1){
		string all[8];
		bool endflg = false;
		for(int i=0; i<8; i++){
			if(!(cin>>all[i])) endflg = true;
			if(endflg) break;
		}
		if(endflg) break;

		for(int i=0; i<7; i++){
			bool breakflg = false;
			for(int j=0; j<7; j++){
				// ツ可。ツづ可個ゥツづゥ
				if(all[i][j]-'0'==1&&all[i][j+1]-'0'==1){
					if(all[i+1][j]-'0'==1&&all[i+1][j+1]-'0'==1){
						ans = "A";
					} else if(all[i+1][j]-'0'==0&&all[i+1][j+1]-'0'==0){
						ans = "C";
					} else if(all[i+1][j]-'0'==1&&all[i+1][j+1]-'0'==0){
						ans = "G";
					} else if(all[i+1][j]-'0'==0&&all[i+1][j+1]-'0'==1){
						ans = "E";
					}
					breakflg = true;
					break;
				}
				// ツ縦ツづ可個ゥツづゥ
				if(all[i][j]-'0'==1&&all[i+1][j]-'0'==1){
					if(all[i][j+1]-'0'==1&&all[i+1][j+1]-'0'==1){
						ans = "A";
					} else if(all[i][j+1]-'0'==0&&all[i+1][j+1]-'0'==0){
						ans = "B";
					} else if(all[i][j+1]-'0'==1&&all[i+1][j+1]-'0'==0){
						ans = "D";
					} else if(all[i][j+1]-'0'==0&&all[i+1][j+1]-'0'==1){
						ans = "F";
					}
					breakflg = true;
					break;
				}
			}
			if(breakflg) break;
		}
		cout<<ans<<endl;
	}
	return 0;
}

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

#define rep(i,a,b) for(int i=a; i<b; i++)
#define loop(i,n) rep(i,0,n)

int main(){
    char b[8][9];
    while(1){
        loop(i,8)if(!(cin>>b[i])) return 0;
        int maxx=-1,maxy=-1,minx=8,miny=8;
        loop(y,8)loop(x,8){
            if(b[y][x]=='1'){
                minx=min(x,minx),miny=min(y,miny);
                maxx=max(x,maxx),maxy=max(y,maxy);
            }
        }
        int dx=maxx-minx,dy=maxy-miny;
        char ans;
        if(dx==1&&dy==1) ans='A';
        else if(dx==0) ans='B';
        else if(dy==0) ans='C';
        else if(b[miny][minx]=='0'){
            if(dx==1) ans='D';
            else ans='G';
        } else {
            if(dx==1) ans='F';
            else ans='E';
        }
        cout<<ans<<endl;
    }
}

C++: #include <iostream>

using namespace std;
int main()
{
  string a[8];
  for(;cin>>a[0];)
    {
      for(int i=1;i<8;i++)
	cin>>a[i];
      char n='X';
      for(int i=0;i<8;i++)
	for(int j=0;j<8;j++)
	  if(a[i][j]=='1')
	    {
	      if(i<7&&j<7&&a[i][j+1]=='1' &&a[i+1][j]=='1' &&a[i+1][j+1]=='1')
		n='A';
	      else if(i<5&&a[i+1][j]=='1' &&a[i+2][j]=='1' &&a[i+3][j]=='1')
		n='B';
	      else if(j<5&&a[i][j+1]=='1' &&a[i][j+2]=='1' &&a[i][j+3]=='1')
		n='C';
	      else if(i<6&&a[i][j+1]=='1' &&a[i-1][j+1]=='1' &&a[i-1][j+2]=='1')
		n='D';
	      else if(i<7&&j<6&&a[i][j+1]=='1' &&a[i+1][j+1]=='1' &&a[i+1][j+2]=='1')
		n='E';
	      else if(i<6&&j<7&&a[i+1][j]=='1' &&a[i+1][j+1]=='1' &&a[i+2][j+1]=='1')
		n='F';
	      
	      if(n!='X')
		break;
	    }
      if(n=='X')
	n='G';
      cout<<n<<endl;

    }
}