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(n,k):
    # print("n = " + str(n))
    # print("k = " + str(k))
    m1 = 1
    m2 = 1
    m3 = 1
    for i in range(1,n+1):
        m1 *= i
    for i in range(1,k+1):
        m2 *= i
    for i in range(1,(n-k)+1):
        m3 *= i
    # print("m1 = " + str(m1))
    # print("m2 = " + str(m2))
    # print("m3 = " + str(m3))
    return (m1 / (m2 * m3))

n,m,t = map(int, raw_input().split())
ans = 0
for i in range(1,(t-4)+1):
    # print(i)
    x = C(m,i)
    y = C(n,t-i)
    # print(x)
    # print(y)
    ans += (x*y)
print(ans)
