import java.io.PrintWriter;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Scanner;

public class Main 
{
	static Scanner cin = new Scanner(System.in);
	static PrintWriter cout = new PrintWriter(System.out, true);

	public static void main(String[] args) 
	{
		BigInteger a,b,c,ans = null;
		while(cin.hasNext())
		{
			c = cin.nextBigInteger();
			b = cin.nextBigInteger();
			a = cin.nextBigInteger();
			for(int i=3;100-i>0;i++)
			{
				ans = a.add(b).add(c);
				c = b;
				b = a;
				a = ans;
			}
			cout.println(ans);
		}
	}
}