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 cmb(a, b):
#   if (b > 0):
#       return ((1.0*a)/b)*cmb(a-1,b-1)
#   else:
#       return 1.0
def rec(depth, v):
    if depth > 0:
        return v * rec(depth-1, v-1)
    return 1
def cmb(a,b):
    return rec(b, a)/rec(b, b)
n,m,t = map(int, raw_input().split())
cnt = 0
for b in xrange(4, n+1):
    g = t - b
    if g < 1:
        continue
    cnt += int(cmb(n,b) * cmb(m,g))
print cnt