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 f(_n):
    s = 1;
    for i in range(2, _n+1):
        s *= i
    return s

def c(_n, _m):
    return f(_n) / f(_m) / f(_n-_m)

s = raw_input().split()

n = int(s[0])
m = int(s[1])
t = int(s[2])

res = 0
for i in range (4, n+1) :
    if( t == i ) :
        break
    #print n, i, m, t-i
    res += c(n, i) * c(m, t-i) ;

print res
