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 <cstdio>
#include <vector>
#include <string>
#include <map>
#include <algorithm>
#include <cmath>
#include <numeric>
#include <stack>
using namespace std;

#define REP(i,n) for(int (i)=0; (i)<(n); (i)++)
#define For(i,a,b) for(int (i)=(a); (i)<(b); (i)++)
#define PUSH(n,v) for(int i=0; i<(n); i++) {int j; cin >> j; v.push_back(j);}

bool hasA(int bd[8][8]) {
    for (int i = 0; i < 7; i++) {
        for (int j = 0; j < 7; j++) {
            if (bd[i][j] && bd[i][j+1] && bd[i+1][j] && bd[i+1][j+1]) return true;
        }
    }
    return false;
}

bool hasB(int bd[8][8]) {
    for (int i = 0; i < 5; i++) {
        for (int j = 0; j < 8; j++) {
            if (bd[i][j] && bd[i+1][j] && bd[i+2][j] && bd[i+3][j]) return true;
        }
    }
    return false;
}

bool hasC(int bd[8][8]) {
    for (int i = 0; i < 8; i++) {
        for (int j = 0; j < 5; j++) {
            if (bd[i][j] && bd[i][j+1] && bd[i][j+2] && bd[i][j+3]) return true;
        }
    }
    return false;
}

bool hasD(int bd[8][8]) {
    for (int i = 0; i < 6; i++) {
        for (int j = 0; j < 7; j++) {
            if (bd[i][j+1] && bd[i+1][j] && bd[i+1][j+1] && bd[i+2][j]) return true;
        }
    }
    return false;
}

bool hasE(int bd[8][8]) {
    for (int i = 0; i < 7; i++) {
        for (int j = 0; j < 6; j++) {
            if (bd[i][j] && bd[i][j+1] && bd[i+1][j+1] && bd[i+1][j+2]) return true;
        }
    }
    return false;
}

bool hasF(int bd[8][8]) {
    for (int i = 0; i < 6; i++) {
        for (int j = 0; j < 7; j++) {
            if (bd[i][j] && bd[i+1][j] && bd[i+1][j+1] && bd[i+2][j+1]) return true;
        }
    }
    return false;
}

bool hasG(int bd[8][8]) {
    for (int i = 0; i < 7; i++) {
        for (int j = 0; j < 6; j++) {
            if (bd[i][j+1] && bd[i][j+2] && bd[i+1][j] && bd[i+1][j+1]) return true;
        }
    }
    return false;
}

int main36() {
    string s;
    int bd[8][8];
    while(cin >> s) {
        REP(i,8) bd[0][i] = s[i] - '0';
        REP(j,7) {
            cin >> s;
            REP(i,8) bd[j+1][i] = s[i] - '0';
        }
        // input ends
        if (hasA(bd)) cout << "A" << endl;
        else if (hasB(bd)) cout << "B" << endl;
        else if (hasC(bd)) cout << "C" << endl;
        else if (hasD(bd)) cout << "D" << endl;
        else if (hasE(bd)) cout << "E" << endl;
        else if (hasF(bd)) cout << "F" << endl;
        else if (hasG(bd)) cout << "G" << endl;
    }
    return 0;
}

C++: // A Figure on Surface
#include <iostream>
#include <string>
#include <cmath>
using namespace std;

string str;
int i,xbase,ybase,ans;
void solve(){
	char ch;
	switch(ans){
		case 11:
			ch = 'A';
			break;
		case 0:
			ch = 'B';
			break;
		case 6:
			ch = 'C';
			break;
		case -110:
			ch = 'D';
			break;
		case 31:
			ch = 'E';
			break;
		case 110:
			ch = 'F';
			break;
		default:
			ch = 'G';
			break;
	}
	cout << ch << endl;
}
void init(){
	i = 0;
	xbase = ybase = 0;
	ans = 0;
}
int main(){
	while(cin >> str){
		for(int j=0;j<8;j++){
			if(str[j]=='1'){
				if(xbase == 0){
					xbase = j;
					ybase = i;
				} else {
					ans += (j-xbase)*pow(10,i-ybase);
				}
			}
		}
		i++;
		if(i==7){
			solve();
			init();
		}
	}
}

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

string field[8];

bool ch(int i,int j)
{
	if(field[i][j] == '1') return true;
	return false;
}

bool Check_A(int i,int j)
{
	if(i+1 < 8 && j+1 < 8)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i,j+1) && ch(i+1,j+1))  return true;
	}
	return false;
}

bool Check_B(int i,int j)
{
	if(i+1 < 8 && i+2 < 8 && i+3 < 8)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i+2,j) && ch(i+3,j)) return true;
	}
	return false;
}

bool Check_C(int i,int j)
{
	if(j+1 < 8 && j+2 < 8 && j+3 < 8)
	{
		if(ch(i,j) && ch(i,j+1) && ch(i,j+2) && ch(i,j+3)) return true;
	}
	return false;
}

bool Check_D(int i,int j)
{
	if(j-1 > 0 && i+1 < 8 && i+2 < 8)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i+2,j) && ch(i,j-1)) return true;
	}
	return false;
}

bool Check_E(int i,int j)
{
	if(i+1 < 8 && j+1 < 8 && j+2 < 8)
	{
		if(ch(i,j) && ch(i,j+1) && ch(i+1,j+1) && ch(i+1,j+2)) return true;
	}
	return false;
}

bool Check_F(int i,int j)
{
	if(i+1 < 8 && i+2 < 8 && i+3 < 8)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i+1,j+1)&& ch(i+2,j+1)) return true;
	}
	return false;
}

bool Check_G(int i,int j)
{
	if(i+1 < 8 && j+1 < 8 && j-1 > 0)
	{
		if(ch(i,j) && ch(i+1,j) && ch(i,j+1) && ch(i+1,j-1)) return true;
	}
	return false;
}

int main()
{
	while(cin >> field[0])
	{
		for(int i=1;i<8;i++)
		{
			cin >> field[i];
		}
		
		bool flag = true;
		for(int i=0;i<8;i++)
		{
			for(int j=0;j<8;j++)
			{
				if(Check_A(i,j) && flag)
				{
					cout << "A" << endl;
					flag = false;
				}

				if(Check_B(i,j) && flag)
				{
					cout << "B" << endl;
					flag = false;
				}

				if(Check_C(i,j) && flag)
				{
					cout << "C" << endl;
					flag = false;
				}

				if(Check_D(i,j) && flag)
				{
					cout << "D" << endl;
					flag = false;
				}				

				if(Check_E(i,j) && flag)
				{
					cout << "E" << endl;
					flag = false;
				}

				if(Check_F(i,j) && flag)
				{
					cout << "F" << endl;
					flag = false;
				}

				if(Check_G(i,j) && flag)
				{
					cout << "G" << endl;
					flag = false;
				}
			}
		}
	}
	return 0;
}