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
#boy: 4->min(t-1+1, n+1)
#girl: 1->min(t-4+1,m+1)
#c(5,4) = (5-4)!/1!    (5-3)!/2!

import math
def Fact(n, m):
    m = max(m, n-m)
  
    ret = 1L
    de = 1
    for (n, de) in zip(xrange(n, n-m, -1), xrange(1, m+1, 1)):
        ret = ret * n / de
    return ret

    
n,m,t = tuple(map(int,raw_input().split(" ")))

x = max(n,m) + 1

arr = [[0 for p in range(x+1)] for q in range(x+1)]


arr[0][0] = 1
for i in range(1,x):
    arr[i][0] = 1
    for j in range(1, i+1):
        #print i, j
        #print arr
        arr[i][j] = arr[i-1][j-1] + arr[i-1][j]
#print arr
bi = max(4, t-m)
result = 0
while bi<=n and bi<=t-1:
#    print bi, arr[n][bi], t-bi, arr[m][t-bi]
    result += arr[n][bi]*arr[m][t-bi]
    bi += 1
    
print result