string crypt(string line, string type, string alphabet, int k){
  if(!strcmp(type.c_str(),"decode")){
       if(k>alphabet.size()) k=-(k%alphabet.size());
       if(k<=alphabet.size()) k=-k;
  }

    for(int i=0;i<strlen(line.c_str());i++){
      for(int j=0;j<alphabet.size();j++){
          if(line[i]==alphabet[j]){
             if(k>alphabet.size()) k=k%alphabet.size();
             int shift=(j+k+alphabet.size())%alphabet.size();
             line[i]=alphabet[shift];
             break;
          }
      }
    }
  return line;
}

void text(string alphabet, string type,int k, string source, string dest){
  string line;
  ifstream fin(source.c_str());
  getline(fin,line);
  line=crypt(line,type,alphabet,k);
  fin.close();
  ofstream fout(dest.c_str());
  for(int i=0;i<strlen(line.c_str());i++){
      fout<<line[i];
  }
  fout.close();
}