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 fact(n):
    r = 1
    for i in range(1, n + 1):
        r *= i
    return(r)

def c(n, k):
    return(fact(n) // ((fact(k)) * (fact(n - k))))

n, m, t = map(int, raw_input().split())
#n = int(inp[0])
#m = int(inp[1])
#t = int(inp[2])
print
ans = 0
for i in range(4, t):
    ans += c(n, i) * c(m, t - i)
    
print(ans)
