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
data=raw_input()
data=data.split()
n=int(data[0])
m=int(data[1])
t=int(data[2])

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

variants=[]
variants.append([4,t-4])

i=0

#print variants

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

while variants[i][1]>1:
    i+=1
    variants.append([variants[i-1][0]+1,variants[i-1][1]-1])

#print variants



for i in range(len(variants)-1):
    if int(variants[i][0])>n or int(variants[i][1])>m:
        variants[i]=''
    else:
        pass

#print variants
summa=0

for i in range(len(variants)):
    if variants[i]!='':
        summa=summa+comb(n,variants[i][0])*comb(m,variants[i][1])
print summa