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 fact(num):
  if (num <= 1): return 1
  else: return num * fact(num - 1)
  
def comb(n, p):
  return fact(n)  / (fact(p)*fact(n-p))

n, m, t = map(int, raw_input().split())
summ = 0
boys = 4
if (n == 4): 
	girls = t - boys
	comb1 = comb(n, boys)
	comb2 = comb(m, girls)
	summ += comb1*comb2
else:
	while (boys < t):
		girls = t - boys
		comb1 = comb(n, boys)
		comb2 = comb(m, girls)
		summ += comb1*comb2
		boys += 1
	
print summ