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

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

    int i;
    long long int sum = 1;
    /* (i = 1; i < k; i++){
        sum =(sum * 2);
        sum = sum % 1000000007;
    }*/
    //printf("mocnina %lld\n", sum);
    long long int pocet = 0;
    pocet = (sum << k)  % 1000000007;
    pocet = ((pocet >> 1) * k)% 1000000007;

    if (a == b && a == c) {
        printf("%d\n", k);
    } else if (c == a || c == b) {
        printf("%lld\n", pocet);
    } else {
        printf("0\n");
    }

    return 0;
}