#include <iostream>
#include <math.h>

int main() {
    using namespace std;
    int a,b,c,k;
    cin >> a >> b >> k >> c;

    if(c != a && c != b) {
        printf("0\n");
        return 0;
    }

    long long result = 1;
    long long maxMult = pow(2, 20);

    int i = k;
    int alpha = 0;
    long long currentMult;

    while(i >= 1) {

        if(i >= 20) {
            alpha = 20;
            currentMult = maxMult;
        } else {
            alpha = i;
            currentMult = pow(2, alpha);
        }

        result *= currentMult;
        result = result % 1000000007;

        i -= alpha;
    }

    cout << ((result * (long long)(k) / 2L) % 1000000007L);

    return 0;
}