import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Barrels {

    public static void main(String[] args) {
        BufferedReader br;
        String[] line;
        double a = 0, b = 0, kDigits = 0, c = 0;
        try {
            br = new BufferedReader(new InputStreamReader(System.in));
            line = br.readLine().split("\\s");
            a = Double.parseDouble(line[0]);
            b = Double.parseDouble(line[1]);
            kDigits = Double.parseDouble(line[2]);
            c = Double.parseDouble(line[3]);
        }
        catch (Exception e) {
            System.out.println(e.getMessage());
        }
        //
        if (c != a || c != b) {
            System.out.println(0);
            return;
        }
        // pocet moznosti / 2
        double res = ((Math.pow(2, kDigits) * kDigits) / 2.0d) % 1000000007;
        System.out.println((int) res);
    }
}