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 comb(n, r):
    if r > n or r <= 0:
        return 0
    return fact[n] // ((fact[r]) * (fact[n-r]))



l= input().split() 
n = int(l[0])
m = int(l[1])
t = int (l[2])
# print(n, m, t)
fact = []
fact.append(1)
fact.append(1)
for i in range(2,31):
    fact.append(i * fact[i-1])
ans = 0
begb = 4
while(begb < t):
    ans+= (comb(n, begb) * comb(m, t - begb))
    begb+= 1
print(ans)


