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
import sys

#sys.stdin = open('in.txt', 'r')

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

dp = [[0] * 31 for _ in xrange(31)]
for i in xrange(0, 31):
	for j in xrange(0, i + 1):
		if i == 0 or j == 0 or i == j:
			dp[i][j] = 1
		else:
			dp[i][j] = dp[i - 1][j] + dp[i - 1][j - 1]
		#print 'dp[%d][%d] = [%d]' % (i, j, dp[i][j])

ans = 0
for i in xrange(4, t):
	if i <= n and t - i <= m:
		ans += dp[n][i] * dp[m][min(t - i, m - t + i)]
print ans
