#include <iostream>
#include <cmath>

uint64_t power(uint64_t a, uint64_t b) {

    uint64_t res = 1;

    while (b) {
        res %= 1000000007;
        res *= a;
        --b;
    }

    return res;

}

uint64_t fact(uint64_t f) {

    //if (f <= 1)  return 1;
    //return f * fact(f - 1);

    uint64_t res = 1;
    while (f > 1) {
        res *= f;
        --f;
    }

    return res;

}

uint64_t permutations(uint64_t a, uint64_t b) {

    uint64_t x = (fact(a) + fact(b));
    uint64_t y = fact(a * b);
    return x/y;

}

int main(int argc, const char * argv[]) {

    //std::cout << fact(1000) << std::endl;
    
    uint64_t a, b, k, c;

    std::cin >> a >> b >> k >> c;

    uint64_t variations = power(2, k);
  
    uint64_t res = variations * k;

    if (a != b) {
        res /= 2;
    }

    res %= 1000000007l;

    std::cout << res << std::endl;

    return 0;

}