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 c(a,b):
	if(b>a):
		return 0;
	if(b==0):
		return 1;
	sum=1;
	d=a-b
	while(a>0):
		sum*=a;
		a=a-1;
	while(b>0):
		sum=sum/b;
		b=b-1;
	while(d>0):
		sum=sum/d;
		d=d-1;  
	return sum;

n,m,t=map(int,raw_input().split());
i=4;
ans=0;
while(i<=n and t-i>=1):
	ans=ans+c(n,i)*c(m,t-i);
	i=i+1;
print ans
