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
fact = []
fact.append(1)
for i in range(1, 31):
    fact.append(fact[i - 1]*i)

n, m, t = map(int, raw_input().split())

boys = min(n, t - 1)
girls = t - boys

resp = 0
while boys >= 4 and girls <= m:
    combb = (fact[n]/fact[boys])/fact[n - boys]
    combg = (fact[m]/fact[girls])/fact[m - girls]
    resp += combb * combg
    boys -= 1
    girls += 1

print(resp)
     	  		  	    			 		  	 	 		