import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    // Complete the fibonacciModified function below.
    static BigInteger fibonacciModified(int t1, int t2, int n) {
        BigInteger a = BigInteger.valueOf(t1);
        BigInteger b = BigInteger.valueOf(t2) , ans;
        ans = BigInteger.valueOf(0);
        for( int i = 3 ; i <= n ; i++ )
        {
            ans = a.add( b.multiply(b) );
            a = b;
            b = ans;
        }
        return ans;
    }

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        String[] t1T2n = scanner.nextLine().split(" ");

        int t1 = Integer.parseInt(t1T2n[0]);

        int t2 = Integer.parseInt(t1T2n[1]);

        int n = Integer.parseInt(t1T2n[2]);

        BigInteger result = fibonacciModified(t1, t2, n);

        bufferedWriter.write(String.valueOf(result));
        bufferedWriter.newLine();

        bufferedWriter.close();

        scanner.close();
    }
}