There are n boys and m girls attending a theatre club. To set a play "The Big Bang Theory", they need to choose a group containing exactly t actors containing no less than 4 boys and no less than one girl. How many ways are there to choose a group? Of course, the variants that only differ in the composition of the troupe are considered different.

Perform all calculations in the 64-bit type: long long for С/С++, int64 for Delphi and long for Java.

Input

The only line of the input data contains three integers n, m, t (4 ≤ n ≤ 30, 1 ≤ m ≤ 30, 5 ≤ t ≤ n + m).

Output

Find the required number of ways.

Please do not use the %lld specificator to read or write 64-bit integers in С++. It is preferred to use cin, cout streams or the %I64d specificator.

Examples

Input

5 2 5


Output

10


Input

4 3 5


Output

3
def fat(num):
    if(num == 0):
        return 1
    return num * fat(num-1)
def comb(a, b):
    return fat(a)//(fat(b) * fat(a-b))

n, m, t = map(int,input().split())
tot = 0
x = t-1
y = 1

while(True):
    if(x < 4): break
    if(x <= n and y <= m):
        combx = comb(n, x)
        comby = comb(m, y)
        tot += (combx * comby)
    x -= 1
    y += 1

print(tot)
 	 		  	 		 					  			 		 		  	