#include <iostream>
#include <list>
#include <vector>
#include <string>
#include <stdio.h>
#include <stdint.h>
#include <iomanip>
using namespace std;

using uint = unsigned int;
using ll = long long;

#define CIN( LL , A ) LL A; cin >> A 
#define GETSEGMENT( A , SEPARATOR ) string A; getline( cin , A , SEPARATOR ) 
#define GETLINE( A ) string A; getline( cin , A ) 
#define FOR_LL( VAR , INITIAL , FINAL_PLUS_ONE ) for( ll VAR = INITIAL ; VAR < FINAL_PLUS_ONE ; VAR ++ ) 
#define FOR_ITR( ARRAY , ITR , END ) for( auto ITR = ARRAY .begin() , END = ARRAY .end() ; ITR != END ; ITR ++ ) 
#define RETURN( LL , ANSWER ) const LL answer_for_contest = ( ANSWER ); cout << answer_for_contest << endl; return 0 
#define DOUBLE( DIGITS , ANSWER ) const double answer_for_contest = ( ANSWER ); cout << fixed << setprecision( DIGITS ) << answer_for_contest << endl; return 0 

template <typename T> inline T Distance( const T& a , const ll& b ){ return a < b ? b - a : a - b; }

int main()
{

  // #GL( 2 , Z / p ^ d Z ) = p ^ ( 4 * d - 3 ) * ( p - 1 ) ^ 2 * ( p + 1 )
  // #GL( 2 , F_2 ) = 2 ^ ( 4 * 1 - 3 ) * ( 2 - 1 ) ^ 2 * ( 2 + 1 ) = 2 * 3 = 6
  ll F[6];
  cin >> F[0] >> F[1];
  FOR_LL( i , 2 , 6 ){
    F[i] = F[i-1] ^ F[i-2];
  }
  CIN( ll , N );
  N %= 6;
  RETURN( ll , F[N] );

}