#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef unsigned u;
typedef vector<int> vi;
typedef pair<int, int> pii;
#define F first;
#define S second;
#define PB push_back;
#define MP make_pair;

#define MOD 1000000007

ull modpow(ull k, ull n, ull acc){
    //cout  << acc << endl;
    if(n < k){
        return modpow(k, n + 1, (acc * 2) % MOD) ;
    }
    return acc * k % MOD;
}

bool EQ(double a, double b) {
    return (fabs(a-b) / (a+b) < DBL_EPSILON);
}

int main( ) {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    // code
    ull a, b, c, k;
    cin >> a >> b >> k >> c;

    if(a == b && a == c){
        cout << k << endl;
        return 0;
    } else if(a != c && b != c){
        cout << 0 << endl;
        return 0;
    }
    cout << modpow(k, 1, 1) << endl;
    return 0;
}