/***************************************************
Ceasar-Shift Encryption

Write a program that reads a key value from the
user (i.e. a number between 0 and 26) and a message 
consisting solely of lowercase letters terminated 
by a '.', and prints the Ceasar Shift encryption
of the message using the key.

Ceasar Shift Encryption is decribed in a problem
from Class 6, so check out the lecture notes there.
***************************************************/
#include <iostream>
using namespace std;

main()
{
  // Read in key value
  int k;
  cout << "Enter key value: ";
  cin >> k;
  
  // Read in message
  cout << "Enter message (terminated by a .): ";
  char c;
  cin >> c;

  // LOOP OVER EACH LETTER IN THE MESSAGE!
  while (c != '.')
  {
    // Compute distance for original letter
    int d;
    d = c - 'a';
    
    // Compute distance for encrypted letter
    int ed;
    ed = (d + k) % 26;
    
    // Compute encrypted letter
    char e;
    e = 'a' + ed;
    
    // Write out encrypted letter
    cout << e;

    // read next letter
    cin >> c;
  }

  cout << "." << endl;

  return 0;
}