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
n, m, t = map(int, input().split())
def nCr(n, r):
    num, denom = 1, 1
    for i in range(1, n+1):
        num *= i
    for i in range(1, r+1):
        denom *= i
    for i in range(1, n-r+1):
        denom *= i
    
    return num//denom
        
ls = []
for i in range(1, t):
    #print(i, t-i)
    if i <= m and t-i <= n and i >= 1 and t-i >= 4:
        ls.append((i, t-i))

#print(ls)

count = 0
for item in ls:
    count += (nCr(n, item[1])*nCr(m, item[0]))
    
print(count)
        