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 <iostream>
#include <string>

int main()
{
    std::string figure[] = {
        "1100000011",
        "1000000010000000100000001",
        "1111",
        "1000000110000001",
        "11000000011",
        "100000001100000001",
        "110000011"
    };

    while (!std::cin.eof()) {
        std::string s = "", tmp;
        for (int i = 0; i < 9; ++i) {
            getline(std::cin, tmp);
            s += tmp;
        }

        for (int i = 0; i < 7; ++i) {
            if (s.find(figure[i]) != std::string::npos) {
                std::cout << static_cast<char>(i + 'A') << std::endl;
                break;
            }
        }
    }
}

C++: #include <iostream>
#include <string>
#include <vector>
using namespace std;
#define rep(i,n) for(int i=0; i<(n); ++i)

string kind = "ABCDEFG";

vector<vector<pair<int,int>>> fig = {
    {{ 1, 0}, { 0, 1}, { 1, 1}}, //A
    {{ 0, 1}, { 0, 2}, { 0, 3}}, //B
    {{ 1, 0}, { 2, 0}, { 3, 0}}, //C
    {{-1, 1}, { 0, 1}, {-1, 2}}, //D
    {{ 1, 0}, { 1, 1}, { 2, 1}}, //E
    {{ 0, 1}, { 1, 1}, { 1, 2}}, //F
    {{ 1, 0}, {-1, 1}, { 0, 1}}  //G
};

int main() {
    int v[8][8];
    while (1) {
        char c;
        rep(i,8) rep(j,8) {
            if ( ! (cin >> c)) return 0;
            v[i][j] = c - '0';
        }
        rep(i,8) rep(j,8) {
            if ( ! v[i][j]) continue;
            rep(k,(int)fig.size()) {
                bool ok = true;
                for (auto p : fig[k]) {
                    int x = j + p.first;
                    int y = i + p.second;
                    if (x < 0 || 8 <= x || y < 0 || 8 <= y || ! v[y][x]) {
                        ok = false;
                        break;
                    }
                }
                if (ok) {
                    cout << kind[k] << endl;
                }
            }
        }
    }
    return 0;
}

C++: //33
#include<iostream>
#include<algorithm>

using namespace std;

int main(){
  for(;;){
    char g[8][8];
    for(int y=0;y<8;y++){
      for(int x=0;x<8;x++){
	if(!(cin>>g[y][x]))return 0;
      }
    }
    for(int y=0;y<8;y++){
      for(int x=0;x<8;x++){
	if(g[y][x]=='1'){
	  int a=0;
	  for(int i=0;i<4;i++){
	    for(int j=0;j<4;j++){
	      a=(a<<1)+(y+i<8&&x+j<8&&g[y+i][x+j]=='1');
	    }
	  }
	  static const int f[]={0xcc00,0x8888,0xf000,0x4c80,0xc600,0x8c40,0x6c00};
	  cout<<char(find(f,f+7,a)-f+'A')<<endl;
	  goto next;
	}
      }
    }
  next:
    ;
  }
  return 0;
}

C++: #include<iostream>
#include<string>
using namespace std;
bool check(int (&field)[8][8],int x,int y){
	if(x<0 || x>=8 || y<0 || y>=8 || (field[y][x] == 0)){
		return false;
	}
	return true;
}

int main(){
	int inptf[8][8] = {0}, i, j, x, y;
	string str;
	char btype;
	while(true){
		i=0;
		while(cin>>str){
			for(j=0;j<8;j++){
				inptf[i][j] = str[j] - '0';
			}
			i++;
			if(i==8) break;
		}
		if(i<8) break;
		for(i=0;i<8;i++){
			for(j=0;j<8;j++){
				if(inptf[i][j] != 0){
					y = i;
					x = j;
					i=j=8;
				}
			}
		}
		if(check(inptf , x, y) &&	//[][] A
		   check(inptf , x, y+1) &&	//[][]
		   check(inptf , x+1, y) &&	
		   check(inptf , x+1, y+1))	
			btype='A';
			
		if(check(inptf , x, y) &&	//[] B
		   check(inptf , x, y+1) &&	//[]
		   check(inptf , x, y+2) &&	//[]
		   check(inptf , x, y+3))	//[]
			btype='B';
		if(check(inptf , x, y) &&	//[][][][] C
		   check(inptf , x+1, y) &&	
		   check(inptf , x+2, y) &&	
		   check(inptf , x+3, y))	
			btype='C';
		if(check(inptf , x, y) &&	//  [] D
		   check(inptf , x, y+1) &&	//[][]
		   check(inptf , x-1, y+1) &&	//[]
		   check(inptf , x-1, y+2) )	
			btype='D';
		if(check(inptf , x, y) &&	//[][] E
		   check(inptf , x+1, y) &&	//  [][]
		   check(inptf , x+1, y+1) &&	
		   check(inptf , x+2, y+1))	
			btype='E';
		if(check(inptf , x, y) &&	//[]   F
		   check(inptf , x, y+1) &&	//[][]
		   check(inptf , x+1, y+1) &&	//  []
		   check(inptf , x+1, y+2))	
			btype='F';
		if(check(inptf , x, y) &&	//  [][]G
		   check(inptf , x+1, y) &&	//[][]
		   check(inptf , x, y+1) &&
		   check(inptf , x-1, y+1))	
			btype='F';
		cout<<btype<<endl;
	}
}

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

int main(){
	int ax, ay;
	char f[12][12];
	bool flag = false;

	for(int y=0 ; y<12 ; y++){
		for(int x=0 ; x<12 ; x++){
			f[y][x] = 0;
		}
	}

	while( 1 ){
		for(int i=0 ; i<8 ; i++) {
			if( scanf("%s", f[i]) == EOF ){
				flag = true;
				break;
			}
		}
		if(flag) break;

		for(int i=0 ; i<64 ; i++){
			if(f[i/8][i%8]=='1'){
				ax = i%8;
				ay = i/8;
				//printf("x:%d y:%d\n", ax,ay);
				break;
			}
		}
		//printf("hoge\n");
		if( f[ay+1][ax]=='1' && f[ay][ax+1]=='1' && f[ay+1][ax+1]=='1' ){
			printf("A\n");
		}else if( f[ay+1][ax]=='1' && f[ay+2][ax]=='1' && f[ay+3][ax]=='1' ){
			printf("B\n");
		}else if( f[ay][ax+1]=='1' && f[ay][ax+2]=='1' && f[ay][ax+3]=='1' ){
			printf("C\n");
		}else if( f[ay][ax+1]=='1' && f[ay+1][ax+1]=='1' && f[ay+1][ax+2]=='1' ){
			printf("E\n");
		}else if( f[ay+1][ax]=='1' && f[ay+1][ax+1]=='1' && f[ay+2][ax+1]=='1' ){
			printf("F\n");
		}else if( f[ay][ax+1]=='1' && f[ay+1][ax]=='1' && f[ay+1][ax-1]=='1' ){
			printf("G\n");
		}else if( f[ay+2][ax-1]=='1' && f[ay+1][ax]=='1' && f[ay+1][ax-1]=='1' ){
			printf("D\n");
		}
	}
	

	return 0;
}