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(), "")
		for j := 0; j < 8; j++ {
			ret[i][j], _ = strconv.Atoi(row[j])
		}
	}
	return ret
}

func main() {
	for {
		var board [][]int
		var ans string
		if board = scanBoard(); reflect.DeepEqual(board, [][]int{}) {
			break
		}
		fmt.Println(board)
		for i := 0; i < 8; i++ {
			for j := 0; j < 8; 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 < 8; 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 < 8; 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 < 8; i++ {
			for j := 0; j < 8; 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 < 8; i++ {
			for j := 0; j < 8; 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 < 8; i++ {
			for j := 0; j < 8; 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 < 8; i++ {
			for j := 0; j < 8; 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>
using namespace std;

bool map[8][8];

char Solve(int x,int y){

  if(x!=7 && map[y][x+1]==1 && y!=7 && map[y+1][x]==1 && map[y+1][x+1]==1)
    return 'A';

  else if(y<=4&&map[y+1][x]==1&&map[y+2][x]==1&&map[y+3][x]==1)
    return 'B';

  else if(x<=4&&map[y][x+1]==1&&map[y][x+2]==1&&map[y][x+3]==1)
    return 'C';

  else if(x>0&&y<=5&&map[y-1][x]==1&&map[y-1][x-1]==1&&map[y-2][x-1]==1)
    return 'D';

  else if(y<7&&x<=5&&map[y][x+1]==1&&map[y+1][x+1]==1&&map[y+1][x+2]==1)
    return 'E';

  else if(x<7&&y<=5&&map[y-1][x]==1&&map[y-1][x+1]==1&&map[y-2][x+1]==1)
    return 'F';

  else
    return 'G';

}

int main(){

  char c;

  while(cin>>c){

    map[0][0]=c-'0';

    for(int i=1; i<8; i++){cin>>c;map[0][i]=c-'0';}
    for(int i=1; i<8; i++)for(int j=0; j<8; j++){cin>>c;map[i][j]=c-'0';}

    int i,j;
    for(i=0; i<8; i++){
      for(j=0; j<8; j++){
        if(map[i][j]==true)goto BREAK;
      }
    }
    BREAK:;

  //  for(int m=0;m<8;m++){for(int n=0;n<8;n++)cout<<map[m][n];cout<<endl;}

    cout << Solve(j,i) << endl;

  //  getchar();

  }


  return 0;

}

C++: //0036
#include<iostream>
using namespace std;

struct ca {
	int x;
	int y;
};

int main() {
	ca l[4];
	char c;
	while (cin >> c){
		int a = 0;
		if (c=='1'){
			l[a].x = 0;
			l[a].y = 0;
		}
		for (int i = 0; i < 8; i++) {
			for (int j = 1; j < 8; j++) {
				cin >> c;
				if (c == '1')
				{
					l[a].x = i;
					l[a].y = j;
					a++;
				}
			}
		}
		int x = l[0].x;
		int y = l[0].y;
		if (l[1].x == x&&l[1].y == y + 1) {
			//[l0][l1]
			//ACEG
			if (l[3].x == x + 1 && l[3].y == y + 1)
				cout << 'A';
			else if (l[3].y == y + 3)
				cout << 'C';
			else if (l[3].x == x + 1 && l[3].y == y + 2)
				cout << 'E';
			else cout << 'G';
		}
		else if (l[1].x == x + 1 && l[1].y == y) {
			/*[l0]
			  [l1]*/
			  //BF
			if (l[3].x == x + 3 && l[3].y == y)
				cout << 'B';
			else cout << 'F';
		}
		else cout << 'D';
		cout << endl;
	}
	cin >> c;
	return 0;
}

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 main() {
    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++: #include <cstdio>
#include <utility>
#include <unordered_map>
using namespace std;

#define gcu getchar_unlocked
#define ii inline int in
#define is inline bool scan
ii(int c) {
	int n = 0;
	bool minus = false; if (c == '-') minus = true, c = gcu();
	do {n = 10 * n + (c - '0'), c = gcu();} while (c >= '0');
	//return n; }
	return minus ? -n : n; }
ii() {return in(gcu());}
is(int &n){int c=gcu();return c==EOF?false:(n=in(c),true);}
is(char &c){c=gcu();gcu();return c!=EOF;}
is(string &s){int c; s = "";
	for(;;){c=gcu();if(c=='\n'||c==' ')return true;else if(c==EOF)return false;s+=c;}}
#undef ii
#define pcu putchar_unlocked
template <typename T>
void out(T n) {
	static char buf[20];
	char *p = buf;
	if(n < 0) pcu('-'), n *= -1;
	if (!n) *p++ = '0';
	else while (n) *p++ = n % 10 + '0', n /= 10;
	while (p != buf) pcu(*--p); }
void out(const char *s){while(*s)pcu(*s++);}
void out(char c){pcu(c);}
void out(string &s){for (char c: s) pcu(c);}
template <typename head, typename... tail>
void out(head&& h, tail&&... t){out(h);out(move(t)...);}
//template <typename T>
//void out(vector<T> &v){for(T &x:v)out(&x == &v[0]?"":" "),out(x);out('\n');}
#undef svo

typedef unsigned long ul;

int main() {
	unordered_map<ul, char> m = {{0x303, 'A'}, {0x1010101, 'B'}, {0xf, 'C'},
		{0x8181, 'D'}, {0x603, 'E'}, {0x20301, 'F'}, {0x183, 'G'}};
	do {
		ul n = 0;
		for (int i = 0; i < 8; i++) {
			for (int j = 0; j < 8; j++)
				n = (n << 1) + gcu() - '0';
			gcu();
		}
		out(m[n / (n & -n)], '\n');
	} while (gcu() == '\n');
}