string crypt(string line, string type, string alphabet, int &k){

  if(k>alphabet.length()) k=k%alphabet.size();
  if(!strcmp(type.c_str(),"decode")){
     k=k*(-1);
  }
    for(int i=0;i<strlen(line.c_str());i++){
        int j=-1;
        while (line[i]==alphabet[++j]);
        int shift shift=(j+k+alphabet.length())%alphabet.length();
        line[i]=alphabet[shift];
    }
  return line;
}