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 java.io.*;
import java.math.BigInteger;
import java.sql.Array;
import java.util.*;

public class TaskC {


	static long nCr(long N, long K)		// O(K)
	{
		if(K > N)
			return 0;
		long res = 1;
		for(int i = 1; i <= K; ++i)
			res = (N - K + i) * res / i;
		return res;
	}

	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		PrintWriter pw = new PrintWriter(System.out);
		
		int n = sc.nextInt();
		int m = sc.nextInt();
		int t = sc.nextInt();
		
		long ans = 0;
		for (int i = 4, j = t - i; j >= 1; j--, i++) {
			ans += nCr(n, i) * nCr(m, j);
		}
		pw.print(ans);
		pw.flush();
		pw.close();
	}

	static class Pair implements Comparable<Pair> {
		int x, y;

		public Pair(int x, int y) {
			this.x = x;
			this.y = y;
		}

		public int compareTo(Pair o) {
			if (x == o.x)
				return y - o.y;
			return x - o.x;
		}

		public String toString() {
			return x + " " + y;
		}
	}

	static class Scanner {
		StringTokenizer st;
		BufferedReader br;

		public Scanner(FileReader r) {
			br = new BufferedReader(r);
		}

		public Scanner(InputStream s) {
			br = new BufferedReader(new InputStreamReader(s));
		}

		public String next() {
			while (st == null || !st.hasMoreTokens()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return st.nextToken();
		}

		public boolean check() {
			if (!st.hasMoreTokens())
				return false;
			return true;
		}

		public int nextInt() {
			return Integer.parseInt(next());
		}

		public long nextLong() {
			return Long.parseLong(next());
		}

		public String nextLine() {
			try {
				return br.readLine();
			} catch (Exception e) {
				throw new RuntimeException(e);
			}
		}

		public double nextDouble() {
			String x = next();
			StringBuilder sb = new StringBuilder("0");
			double res = 0, f = 1;
			boolean dec = false, neg = false;
			int start = 0;
			if (x.charAt(0) == '-') {
				neg = true;
				start++;
			}
			for (int i = start; i < x.length(); i++)
				if (x.charAt(i) == '.') {
					res = Long.parseLong(sb.toString());
					sb = new StringBuilder("0");
					dec = true;
				} else {
					sb.append(x.charAt(i));
					if (dec)
						f *= 10;
				}
			res += Long.parseLong(sb.toString()) / f;
			return res * (neg ? -1 : 1);
		}

		public boolean ready() {
			try {
				return br.ready();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
	}
}