Go: package main

import (
	"bufio"
	"os"
	"strings"
	"strconv"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	var scanner = bufio.NewScanner(os.Stdin)
	board := make([][]int, 8)
	for i := range board {
		board[i] = make([]int, 8)
			for j := range board[i] {
				board[i][j] = 0
			}
	}
	var ans string
	for scanner.Scan() {
		tmp := strings.Split(scanner.Text(), "")
		for i := 0; i < 8; i++ {
			board[0][i], _ = strconv.Atoi(tmp[i])
		}
		for i := 1; i < 8; i++ {
			scanner.Scan()
			row := strings.Split(scanner.Text(), "")
			for j := 0; j < 8; j++ {
				board[i][j], _ = strconv.Atoi(row[j])
			}
		}
		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>

using namespace std;

int board[8][9];//y,xの順番

char data[10];

int isA(int x,int y){

	if(y==7 || x == 7){
		return 0;
	}
	if(board[y][x+1] == 1 && board[y+1][x+1] == 1 && board[y+1][x] == 1){
		return 1;
	}

	return 0;
}

int isB(int x,int y){
	if(y>=5){
		return 0;
	}
	else if(board[y+1][x]==1 && board[y+2][x] == 1 && board[y+3][x]==1){
		return 1;
	}

	return 0;
}

int isC(int x,int y){
	if(x>=5){
		return 0;
	}
	else if(board[y][x+1]==1 && board[y][x+2] == 1 && board[y][x+3]==1){
		return 1;
	}

	return 0;
}

int isD(int x,int y){
	if(y>=6 || x==0){
		return 0;
	}
	else if(board[y+1][x]==1 && board[y+2][x-1] == 1 && board[y+1][x-1]==1){
		return 1;
	}

	return 0;
}

int isE(int x,int y){
	if(x>=6 || y == 7){
		return 0;
	}
	else if(board[y][x+1]==1 && board[y+1][x+1] == 1 && board[y+1][x+2]==1){
		return 1;
	}

	return 0;
}

int isF(int x,int y){
	if(y>=6 || x==7){
		return 0;
	}
	else if(board[y+1][x]==1 && board[y+1][x+1] == 1 && board[y+2][x+1]==1){
		return 1;
	}

	return 0;
}

int isG(int x,int y){
	if(y==0 || x>=6){
		return 0;
	}
	else if(board[y][x+1]==1 && board[y-1][x+1] == 1 && board[y-1][x+2]==1){
		return 1;
	}

	return 0;
}

void dataChange(int i){
	for(int j=0;j<8;j++){
		board[i][j] = data[j] - '0';
	}
}

int main(){

	while(cin>>data){
		dataChange(0);

		for(int i=1;i<8;i++){
			cin>>data;
			dataChange(i);
		}

		for(int y=0;y<8;y++){
			for(int x=0;x<8;x++){
				if(board[y][x] == 1){
					if(isA(x,y) == 1){
						cout<<"A"<<endl;
					}
				}

				if(board[y][x] == 1){
					if(isB(x,y) == 1){
						cout<<"B"<<endl;
					}
				}
				if(board[y][x] == 1){
					if(isC(x,y) == 1){
						cout<<"C"<<endl;
					}
				}
				if(board[y][x] == 1){
					if(isD(x,y) == 1){
						cout<<"D"<<endl;
					}
				}
				if(board[y][x] == 1){
					if(isE(x,y) == 1){
						cout<<"E"<<endl;
					}
				}
				if(board[y][x] == 1){
					if(isF(x,y) == 1){
						cout<<"F"<<endl;
					}
				}
				if(board[y][x] == 1){
					if(isG(x,y) == 1){
						cout<<"G"<<endl;
					}
				}
			}
		}
	}

	return 0;
}

C++: /*#include<iostream>
#include<string>
#include<vector>
#include<cstdio>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<map>
#include<functional>
#include<queue>
#include<stack>
#include<set>
using namespace std;
int main(){
int n;
cin>>n;
for(int i=0;i<n;i++){
	double x1,y1,x2,y2,x3,y3,x4,y4;
	bool f=0;
	cin>>x1>>y1>>x2>>y2>>x3>>y3>>x4>>y4;
	double yy1=(y2-y1),yy2=y4-y3;
	if(yy1==0)yy1=0.0000001;
	if(yy2==0)yy2=0.0000001;
	double r1=(x2-x1) / (y2-y1);
	double r2=(x4-x3) / (y4-y3);
	if(abs(r1-r2 ) <=0.000001  )f=1;
	if(f)cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
	}
	return 0;
}*/

/*#include<iostream>
#include<string>
#include<vector>
#include<cstdio>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<map>
#include<functional>
#include<queue>
#include<stack>
#include<set>
using namespace std;
int stoi(string x){stringstream ss;ss<<x;int tmp;ss>>tmp;return tmp;}
string itos(int x){stringstream ss;ss<<x;return ss.str();}
char ta[50][50];
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
char a[]={'R','D','L','U'};
vector<char>ans;
void dfs(int y,int x,char now){
	bool f=1;
	for(int i=0;i<4;i++){
		if(a[i]==now&&ta[y+dy[i]][x+dx[i]]=='1'){
			ans.push_back(a[i]);
			f=1;
			dfs(y+dy[i],x+dx[i],now);
		}
	}
	if(f){
		for(int i=0;i<4;i++){
			if(ta[y+dy[i]][x+dx[i]]=='1'){
				ans.push_back(a[i]);
				dfs(y+dy[i],x+dx[i],a[i]);
			}
		}
	}
}

int main(){


	for(int i=0;i<9;i++){
		for(int j=0;j<4;j++){
			char now;
			cin>>now;
			ta[i][j]=now;
		}
	}
		dfs(0,0,'F');
		for(int i=0;i<ans.size();i++)cout<<ans[i];
		ans.clear();
	return 0;
}*/


#include<iostream>
#include<string>
#include<vector>
#include<cstdio>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<map>
#include<functional>
#include<queue>
#include<stack>
#include<set>
using namespace std;
int stoi(string x){stringstream ss;ss<<x;int tmp;ss>>tmp;return tmp;}
string itos(int x){stringstream ss;ss<<x;return ss.str();}
char ta[12][12];

bool ok(int y,int x){
	if(y<0||x<0||y>7||x>7)return 0;
	if(ta[y][x]=='1')return 1;
	return 0;
}
int main(){

while(cin>>ta[0][0]){
	int y,x;
	bool f=1;
	for(int i=0;i<8;i++){
		for(int j=(i==0);j<8;j++){
			char now;
			cin>>now;
			if(now=='1'){
			y=i,x=j;
	if( ok(y,x+1)&ok(y+1,x)&&ok(y+1,x+1) ){cout<<"A";f=0;}
	
	else if( ok(y+1,x)&&ok(y+2,x)&&ok(y+3,x) ){cout<<"B";f=0;}
	
	else if( ok(y,x+1)&&ok(y,x+2)&&ok(y,x+3) ){cout<<"C";f=0;}
	
	else if( ok(y+2,x-1)&&ok(y+1,x-1)&&ok(y+1,x)){cout<<"C";f=0;}
	
	else if( ok(y,x+1)&ok(y+1,x+1)&&ok(y+1,x+2) ){cout<<"E";f=0;}
	
	else if( ok(y+1,x)&&ok(y+1,x+1) &&ok(y+2,x+1)){cout<<"F";f=0;}
	
	else if( ok(y,x+1)&&ok(y+1,x)&&ok(y+1,x-1) ){cout<<"G";f=0;}
	
	if(f==0){cout<<endl;goto end;}
			}
			ta[i][j]=now;
		}
	}
	end:;
		for(int i=0;i<8;i++)for(int j=0;j<8;j++)ta[i][j]='0';
}
	
	return 0;
}

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

char n[12][12];
char figure[7][4][5] = {
	{"1100","1100","0000","0000"},
	{"1000","1000","1000","1000"},
	{"1111","0000","0000","0000"},
	{"0100","1100","1000","0000"},
	{"1100","0110","0000","0000"},
	{"1000","1100","0100","0000"},
	{"0110","1100","0000","0000"}
};


void clear(){
	for(int i=0; i<12; i++)
		for(int j=0; j<12; j++)
			n[i][j]='0';
}

int main(){
	clear();
	while(~scanf("%8s\n%8s\n%8s\n%8s\n%8s\n%8s\n%8s\n%8s", n[0], n[1], n[2], n[3], n[4], n[5], n[6], n[7])){

		for(int i=0; i<7; i++){
			for(int j=0; j<8; j++){
				for(int k=0; k<8; k++){
					bool flag=true;
					
					for(int x=0; x<4; x++){
						for(int y=0; y<4; y++){
							if(figure[i][x][y] != n[j+x][k+y]) flag = false;
						}
					}
					
					if(flag){
						cout << (char)('A'+i) << endl;
					}

				}
			}
		}
		clear();
	}
	return 0;
}