import java.math.*; import java.util.*; import java.io.*; public class Main { public static void main(String[] args) { Scanner cin = new Scanner(new BufferedInputStream(System.in)); BigInteger a,b,c,d; while ( cin.hasNext() ) { a = cin.nextBigInteger(); b = cin.nextBigInteger(); c = cin.nextBigInteger(); d = BigInteger.valueOf(0); for (int i = 3; i <= 99; i++) { if ( i % 4 == 3 ) d = a.add(b.add(c)); else if ( i % 4 == 0 ) a = b.add(c.add(d)); else if ( i % 4 == 1 ) b = c.add(d.add(a)); else c = d.add(a.add(b)); } System.out.println(d); } } }