#include <fstream>
#include <iostream>
#include <vector>
#include <map>

const std::string letters="ABCDEFGHIJKLMNOP";

class Sudoku{
private:
    const int ROWS_NUM=16;
    const int COLS_NUM=16;
    const int NUM=16;
    const int PEERS_SZ=39;

    std::map<std::string,std::string> values;
    std::map<std::string,std::vector<std::string>> peers;

public:
    Sudoku(){
        initPeers(); //init peers
        initValues();
    }
    void solve(){

    }
    void initValues(){
        std::string str;
        //for each cell
        for(int i=0;i<ROWS_NUM;i++){
            for(int j=0;j<COLS_NUM;j++){
                str="";
                str+=letters[i];
                str+=letters[j];
                values.insert(std::pair<std::string,std::string>(str,letters));
            }
        }
    }
    void initPeers(){
        //init peers
        int x,y;
        std::string str;
        std::string strk;
        std::vector<std::string> vect;
        //for each cell
        for(int i=0;i<ROWS_NUM;i++){
            for(int j=0;j<COLS_NUM;j++){
                str="";
                str+=letters[i];
                str+=letters[j];
                vect.clear();
                //rows
                for(int k=0;k<ROWS_NUM;k++){
                    if(k!=i){
                        strk="";
                        strk+=letters[k];
                        strk+=letters[j];
                        vect.push_back(strk);
                    }
                }
                //columns
                for(int k=0;k<COLS_NUM;k++){
                    if(k!=j){
                        strk="";
                        strk+=letters[i];
                        strk+=letters[k];
                        vect.push_back(strk);
                    }
                }
                y=i/4;
                x=j/4;
                //square
                for(int ii=0; ii<NUM/4; ii++){
                    for(int jj=0; jj<NUM/4; jj++){
                        if(ii!=i && jj!=j){
                            strk="";
                            strk+=letters[y+ii];
                            strk+=letters[x+jj];
                            vect.push_back(strk);
                        }
                    }
                }
                peers.insert(std::pair<std::string, std::vector<std::string>>(str, vect));
            }
        }
        //        TEST UNITS
        //        std::string st="CC";
        //        for(int i=0;i<units[st].size();i++){
        //            std::cout<<units[st][i]<<" ";
        //        }
        //        std::cout<<std::endl<<units[st].size()<<std::endl;
    }

    void read(std::string fileName){
        std::ifstream fin(fileName);
        char c;
        std::string str;
        for(int i=0;i<ROWS_NUM;i++){
            for(int j=0;j<COLS_NUM;j++){
                str="";
                fin>>c;
                str+=letters[i];
                str+=letters[j];
                insert(str, c);
            }
        }
        fin.close();
    }
    void insert(std::string square, char val){
        if(val=='-'){
            //            values.insert(std::pair<std::string, std::string>(square,letters));
        } else{
            assign(square, val);
        }

    }
    void assign(std::string square, char val){
        values[square]=std::string(1,val);
        std::string *str;
        for(int i=0;i<PEERS_SZ;i++){
            str= &values[peers[square][i]];
//            if((*str).size()==1){
//                continue;
//            }
            (*str).erase(std::remove((*str).begin(), (*str).end(), val));
        }
    }
    void write(std::string fileName){
        std::ofstream fout(fileName);
        std::string str,str1;
        for(int i=0;i<ROWS_NUM;i++){
            for(int j=0;j<COLS_NUM;j++){
                str="";
                str+=letters[i];
                str+=letters[j];
                str1=values[str];
                fout<<str1<<"\t";
            }
            fout<<"\n";
        }
        fout.close();
    }
};

int main(int argc, const char * argv[]) {
    Sudoku sudoku;
    sudoku.read("input.txt");
    sudoku.solve();
    sudoku.write("output.txt");

    //    std::cout<<"GGG\n";
    //    char c1;
    //    while(true){
    //        std::cin>>c1;
    //        std::cout<<sudoku.ctoi(c1)<<std::endl;
    //        std::cout<<sudoku.itoc(sudoku.ctoi(c1))<<std::endl;
    //    }
    return 0;
}