#include <stdio.h>
#include <math.h>

int main() {
    int a,b,c,k;
    scanf("%d %d %d %d", &a, &b, &k, &c);

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

    int result = 1;
    int maxMult = pow(2, 29);

    int i = k;
    while(i > 1) {
        // 2^29
        int currentMult = i >= 29 ? maxMult : pow(2, i);
        result *= currentMult;

        i -= currentMult;

        result = result % 1000000007;
    }

    printf("%d\n", (result * k / 2) % 1000000007);

    return 0;
}