#include<vector>
#include<iostream>

using namespace std;

void com(vector<int> &v, int &a, int &b, int &k, int c, int num){
	if(c == k){
		num /= 10;
		v.push_back(num);
		return;
	}

	num += a;
	num *= 10;
	com(v, a, b, k, c+1, num);
	num /= 10;
	num -= a;

	num += b;
	num *= 10;
	com(v, a, b, k, c+1, num);
}

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

	if(c == a || c == b){
		vector<int> v;
		com(v, a, b, k, 0, 0);

		unsigned int sum = 0;

		for(unsigned int i = 0; i < v.size(); ++i){
			for(int d = 0; d < k; ++d){
				int num = v[i];
				if(num % 10 == c){
					++sum;
					sum %= 1000000007;
				}
				num /= 10;		
			}
		}

		cout << sum << "\n";
	}else{
		cout << 0 << "\n";
	}

	return 0;
}