Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		N, K, S := io.NextInt(), io.NextInt(), io.NextInt()
		if N == 0 {
			break
		}
		dp := [21][11][156]int{}
		for i := 0; i <= N; i++ {
			dp[i][0][0] = 1
		}
		for i := 1; i <= N; i++ {
			for j := 1; j <= K; j++ {
				for k := 1; k <= S; k++ {
					if k-i >= 0 {
						dp[i][j][k] += dp[i-1][j-1][k-i]
					}
					dp[i][j][k] += dp[i-1][j][k]
				}
			}
		}
		io.Println(dp[N][K][S])
	}
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := make([]interface{}, 0, len(a))
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := make([]interface{}, 0, len(a))
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

C++: #pragma GCC optimize("O3")
#include<bits/stdc++.h> 
using namespace std;
using ll=long long;
using ull=unsigned long long int;
using P=pair<ll,ll>;
template<class T> using V=vector<T>; 
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
const ll inf=(1e18);
const ll mod=1000000007;
ll gcd(ll a,ll b) {return b ? gcd(b,a%b):a;}
ll lcm(ll c,ll d){return c/gcd(c,d)*d;}
struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}} __init;
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
ll dp[11][205];
int main(){
while(1){
  ll n,k,s;
  cin>>n>>k>>s;
  if(n==0)return 0;
  for(int i=0;i<11;i++)for(int j=0;j<205;j++)dp[i][j]=0;
  dp[0][0]=1;
  for(int i=1;i<=n;i++){
    for(int j=k-1;j>=0;j--){
      for(int r=0;r<=s;r++){
        if(dp[j][r]){
          if(i+r<=s)dp[j+1][i+r]+=dp[j][r];
        }
      }
    }
  }
  cout<<dp[k][s]<<"\n";
}
}

C++: #include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <algorithm>
#include <numeric>

using namespace std;
using ll = long long;

int main()
{
    while (true) {
        int n, k, s;
        cin >> n >> k >> s;
        if (n == 0 and k == 0 and s == 0) {
            break;
        }
        vector<vector<int>> dp(n + 1, vector<int>(s + 1, 0));  // ?????????i??§??????j
        for (int i = 1; i <= min(n, s); i++) {
            dp[i][i] = 1;
        }
        for (int l = 1; l < k; l++) {
            auto tmp = dp;
            fill(dp.begin(), dp.end(), vector<int>(s + 1, 0));
            for (int i = 0; i <= n; i++) {
                for (int j = 0; j <= s; j++) {
                    if (tmp[i][j] > 0) {
                        for (int m = i + 1; m <= min(n, s - j); m++) {
                            dp[m][j + m] += tmp[i][j];
                        }
                    }
                }
            }
        }
        int sum = 0;
        for (int i = 0; i <= n; i++) {
            sum += dp[i][s];
        }
        cout << sum << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <vector>
#include <algorithm>
#include <set>
#include <queue>
#include <map>
#include <climits>
using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define RREP(i,n) for(int i=(int)n-1; i>=0; i--)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define RFOR(i,c) for(__typeof((c).rbegin())i=(c).rbegin();i!=(c).rend();++i)
#define ALL(c) (c).begin(), (c).end()

typedef long long int ll;
typedef pair<int, int> pii;
typedef pair<int, pair<int, int> > pipii;
typedef vector<int> vi;

const int INF = 1e9;
const int MOD = 1e9+7;

int n, k, s;

ll dfs(int n, int k, int s){
    if(n < 0 || s < 0) return 0;
    if(!k){
        if(!s) return 1;
        else return 0;
    }
    ll ret = 0;
    ret += dfs(n - 1, k - 1, s - n);
    ret += dfs(n - 1, k, s);
    return ret;
}

int main(void){
    while(cin >> n >> k >> s, n){
        cout << dfs(n, k, s) << endl;
    }
}

C++: #include <algorithm>
#include <bitset>
#include <cctype>
#include <complex>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

using namespace std;

inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}
template<class T> inline T sqr(T x) {return x*x;}

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;

#define all(a)  (a).begin(),(a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define pb push_back
#define mp make_pair
#define each(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define exist(s,e) ((s).find(e)!=(s).end())
#define range(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)  range(i,0,n)
#define clr(a,b) memset((a), (b) ,sizeof(a))
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

const double eps = 1e-10;
const double pi  = acos(-1.0);
const ll INF =1LL << 62;
const int inf =1 << 29;

int n, k, s;
int res;

void dfs(int, int, int);

int main(void){
    for(; cin >> n >> k >> s, n; cout << res << endl){
        res = 0;
        dfs(0, 0, k);
    }

	return 0;
}

void dfs(int pre, int sum, int rest){
    if(rest-- == 0){
        if(sum == s) res++;
        return;
    }
    range(i, pre + 1, n + 1){
        dfs(i, sum + i, rest);
    }
}