import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        try {
            int T = 1;
            for (int i = 0; i < T; ++i) {
                Runner runner = new Runner(br, bw);
                runner.run();
                runner.flush();
            }
            br.close();
            bw.close();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

class Solution {
    int[][][] dp = new int[21][21][21];

    int w(int a, int b, int c) {
        if (a <= 0 || b <= 0 || c <= 0)
            return 1;
        if (a > 20 || b > 20 || c > 20)
            return w(20, 20, 20);
        if (dp[a][b][c] != 0)
            return dp[a][b][c];
        if (a < b && b < c)
            return dp[a][b][c] = w(a, b, c - 1) + w(a, b - 1, c - 1) - w(a, b - 1, c);
        return dp[a][b][c] = w(a - 1, b, c) + w(a - 1, b - 1, c) + w(a - 1, b, c - 1) - w(a - 1, b - 1, c - 1);
    }

    String solution(int a, int b, int c) {
        return format(a, b, c, w(a, b, c));
    }

    String format(int a, int b, int c, int res) {
        return String.format("w(%d, %d, %d) = %d\n", a, b, c, res);
    }
}

class Runner {
    final Reader reader;
    final BufferedWriter bw;

    Runner(BufferedReader br, BufferedWriter bw) {
        this.reader = new Reader(br);
        this.bw = bw;
        try {

        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public void flush() {
        try {
            bw.write('\n');
            bw.flush();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public void run() throws IOException {
        var sol = new Solution();
        while (true) {
            var abc = reader.readInts();
            if (abc[0] == -1 && abc[1] == -1 && abc[2] == -1)
                break;
            var res = sol.solution(abc[0], abc[1], abc[2]);
            bw.write(String.valueOf(res));
        }
    }
}

class Reader {
    private BufferedReader br;

    public Reader(BufferedReader br) {
        this.br = br;
    }

    public int[] readInts() throws IOException {
        StringTokenizer st = new StringTokenizer(br.readLine(), " ");
        int cnt = st.countTokens();
        int[] ints = new int[cnt];
        for (int i = 0; i < cnt; ++i) {
            ints[i] = Integer.parseInt(st.nextToken());
        }
        return ints;
    }
}