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
ncr={};
def fncr(n,r):
	if r==0 or r==n:
		ncr[n][r]=1;
		ncr[n][n-r]=ncr[n][r];
		return;
	else:
		ncr[n][r]=ncr[n-1][r-1]+ncr[n-1][r]
		ncr[n][n-r]=ncr[n][r]
 
for i in range(0,35):
	ncr[i]={}
for i in range(0,35):
	ncr[i][0]=1
	ncr[i][i]=1
for i in range(1,35):
	for j in range(1,35):
		if j<=i:
			fncr(i,j)
		else:
			break
 
x=raw_input()
x=x.split(' ')
n=int(x[0])
m=int(x[1])
t=int(x[2])
ans=0
y=n+1
for j in range(4,y):
	if j<=n and t-j<=m and t-j>=1:
		ans += (ncr[n][j]*ncr[m][t-j]);
print ans;
 
