Problem: Our hero - Maga has been working on a research related to Pascal’s Triangle for about a month. He has recently found a new problematic thing for his research. He has to calculate a big number. But he is very busy. Could you do it for him?

You are given a binomial as this: (a * x + b * y)^n. You have to find the binomial coefficient of x^k * y^(n-k) modulo 10^9+7.

Input:

You are given 4 integers: each space separated integers a, b, n and k.

Output:

Output 1 integer: the binomial coefficient of x^k * y^(n-k) mod (10^9+7).

Constraints:

1 ≤ a, b ≤ 100

1 ≤ n ≤ 10^6

1 ≤ k ≤ min(n,10^5)

SAMPLE INPUT
1 1 4 2

SAMPLE OUTPUT
6

Explanation

The result is 6. In the (x+y)^4 binomial, the coefficient of x^2 * y^2 is 6.

Solution (in PYTHON):

Solution:
import sys
f = sys.stdin
mod = 1000000007

def inv(x,y):
	res = 1
	while y:
		if y%2:
			res = res*x%mod
		y/=2
		x=x*x%mod
	return res
	
a,b,n,k = [int(x) for x in f.readline().split()]
num = 1
deno = 1
for i in range(1,n+1):
	num = num*i%mod

for i in range(1,k+1):
	deno = deno*i%mod
	num = num*a%mod
for i in range(1,n-k+1):
	deno = deno*i%mod
	num=num*b%mod

print num*inv(deno,mod-2)%mod