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
# Python3 implementation to find nCr 

from math import *

# Function to find the nCr 
def printNcR(n, r): 

	# p holds the value of n*(n-1)*(n-2)..., 
	# k holds the value of r*(r-1)... 
	p = 1
	k = 1

	# C(n, r) == C(n, n-r), 
	# choosing the smaller value 
	if (n - r < r): 
		r = n - r 

	if (r != 0): 
		while (r): 
			p *= n 
			k *= r 

			# gcd of p, k 
			m = gcd(p, k) 

			# dividing by gcd, to simplify product 
			# division by their gcd saves from the overflow 
			p //= m 
			k //= m 

			n -= 1
			r -= 1

		# k should be simplified to 1 
		# as C(n, r) is a natural number 
		# (denominator should be 1 ) 

	else: 
		p = 1

	# if our approach is correct p = ans and k =1 
	return p 




n,m,t =map(int,input().split())
ans=0

b=max(4,t-m)
tt = max(1,t-n)
while(True):
    
        g=t-b
        if g>=tt:
            ans+=(printNcR(n,b))*(printNcR(m,g))
            b+=1
        else:
            break
        
        
    
print(int(ans))