#include "bits/stdc++.h"

#define REP(i,num) for(int i=0;i<(num);++i)
#define LOOP(i) while(i--)
#define ALL(c) c.begin(),c.end()
#define PRINTALL(c) for(auto& x:c){cout<<x<<' ';}cout<<endl;
#define PAIRCOMP(c,comp) [](const pair<ll,ll>& lhs,const pair<ll,ll>& rhs){return lhs.c comp rhs.c;}

using namespace std;
using ll = long long;

constexpr ll atcoder_mod = 1e9+7;

template<typename T=int>
T in(){T x; cin >> x; return (x);}
template<typename T=int,typename C=vector<T>>
C vecin(int N){C x(N);REP(i,N){x[i]=in<T>();}return move(x);}

void vout(){cout << endl;}
template<typename Head,typename... Tail>
void vout(Head&& h,Tail&&... t){cout << ' ' << h;vout(forward<Tail>(t)...);}
void out(){cout << endl;}
template<typename Head,typename... Tail>
void out(Head&& h,Tail&&... t){cout << h;vout(forward<Tail>(t)...);}

vector<string> split_naive(const string &s, char delim) {
	vector<string> elems;
	string item;
	for(char ch:s){
		if(ch==delim){
			if(!item.empty()) elems.push_back(item);
			item.clear();
		}
		else{
			item += ch;
		}
	}
	if(!item.empty()) elems.push_back(item);
	return elems;
}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	while(true){
		vector<vector<int>> T(8,vector<int>(8));
		int LX=10,RX=-1,TY=10,BY=-1;
		REP(i,8){
			string S;
			if(!(cin>>S)){
				return 0;
			}
			REP(j,8){
				T[i][j] = S[j]-'0';
				if(T[i][j]){
					LX = min(LX,j);
					RX = max(RX,j);
					TY = min(TY,i);
					BY = max(BY,i);
				}
			}
		}
		if(RX-LX==1 && BY-TY==1){
			out('A');
		}
		else if(RX-LX==0 && BY-TY==3){
			out('B');
		}
		else if(RX-LX==3 && BY-TY==0){
			out('C');
		}
		else if(RX-LX==1 && BY-TY==2){
			if(T[TY][LX]) out('F');
			else out('D');
		}
		else{
			if(T[TY][LX]) out('E');
			else out('G');
		}
	}
	
	return 0;
}
