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++: #define	_USE_MATH_DEFINES
#include <iostream>
#include <iomanip>
#include <cctype>
#include <cstdlib>
#include <algorithm>
#include <functional>
#include <vector>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cfloat>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <string>
#include <set>
#include <complex>
#include <utility>
#include <numeric>
#define  rep(i,n) for(int i=0;i<(n);i++)
#define  REP(i,a,n) for(int i=a;i<(n);i++)
#define  rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define  VI	vector<int>
#define	 VS vector<string>
#define  all(a) (a).begin(),(a).end()
#define  debug(x) cout<<#x<<": "<<x<<endl

using namespace std;
typedef long long int ll;
typedef string::const_iterator State;
typedef pair<int,int> P;
class ParseError {};
const ll INF=1LL<<50;
char fi[101][101];
int day[12]={31,28,31,30,31,30,31,31,30,31,30,31};
double EPS = 1e-14;
const int MAX_V=100;
const int MAX_N=100;
char o[3]={'+','-','*'};
#define md 1000003



int bow[353][353]={0};
double add(double a,double b){
	if(abs(a+b)<EPS*(abs(a)+abs(b)))
	return 0;
	return a+b;
}

/*struct P{
	double x,y;
	P(){}
		P(double x,double y):x(x),y(y){
		}
		P operator + (P p){
			return P(add(x,p.x),add(y,p.y));
		}
		P operator - (P p){
			return P(add(x,-p.x),add(y,-p.y));
		}
		P operator *(double d){
			return P(x*d,y*d);
		}
		double dot(P p){
			return add(x*p.x,y*p.y);
		}
		double det(P p){
			return add(x*p.y,-y*p.x);
		}
};

bool cmp_x(const P& p,const P& q){
	if(p.x!=q.x) return p.x<q.x;
	return p.y<q.y;
}

vector<P> convex_hull(P* ps, int n){
	sort(ps,ps+n,cmp_x);
	int k=0;
	vector<P> 	qs(n*2);
	
	rep(i,n){
		while(k>1&&(qs[k-1]-qs[k-2]).det(ps[i]-qs[k-1])<=0)
			k--;
		qs[k++]=ps[i];
	}
	for(int i=n-2,t=k;i>=0;i--){
		while(k>t&&(qs[k-1]-qs[k-2]).det(ps[i]-qs[k-1])<=0)
		k--;
		qs[k++]=ps[i];
	}
	qs.resize(k-1);
	return qs;
}

int n,m;
vector<double> p;
P ps[101];
*/
//char c[520][520];
long long mod=1000000007;
long long pow(ll i,ll j){
	ll tmp=1;
	while(j){
		if(j%2) tmp=tmp*i%mod;
		i=i*i%mod;
		j/=2;
	}
	return tmp;
}

int expression(State&);
int term(State&);
int factor(State&);
int number(State&);
int expression(State &begin){
	int ret = term(begin);
	
	for(;;){
		if(*begin == '+'){
			begin++;
			ret += term(begin);
		}
		else if(*begin == '-'){
			begin++;
			ret -= term(begin);
		}
		else
			break;
	}
	return ret;
}

int term(State &begin){
	int ret = factor(begin);
	
	for(;;){
		if(*begin=='*'){
			begin++;
			ret *= factor(begin);
		}
		else if(*begin=='/'){
			begin++;
			ret /= factor(begin);
		}
		else
			break;
	}
	return ret;
}

int factor(State &begin){
	int ret;
	if(*begin == '('){
		begin++;
		ret = expression(begin);
		begin++;
	}
	else
	ret = number(begin);
	
	return ret;

}

int number(State &begin){
	int ret =0;
	
	while(isdigit(*begin)){
		ret*=10;
		ret+=*begin - '0';
		begin++;
	}
	return ret;
}

ll n,ans;

void tansaku(int k,int s,set<int> f){
	
	if(s==0&&k==0)
		ans++;
	else if(s<=0||k<=0){
		return;
	}
	else{
	for(int i=1;i<=n;i++){
		if(f.count(i)==0){
			f.insert(i);
		 tansaku(k-1,s-i,f);
		}
	}
	}

}


int main(void){
	ll k,s;
	while(cin>>n>>k>>s,n!=0||k!=0||s!=0){
		set<int> f;
		ans=0;
		tansaku(k,s,f);
		cout<<ans<<endl;
	}

	
}

C++: #include <numeric>
#include <vector>
#include <algorithm>
#include <cstdio>
using namespace std;

int main(){
    int n,k,s,i,c,res;
    while(1){
        scanf("%d",&n);
        scanf("%d",&k);
        scanf("%d",&s);
        if(!n && !k && !s){break;}
        vector<int> t(n,0);
        vector<int> cd(n);
        iota(cd.begin(),cd.end(),1);
        for(i=0;i<k;i++){t[n-i-1]=1;}    
        res=0;
        do{
            c=0;
            for(i=0;i<n;i++){c+=(t[i]*cd[i]);}
            if(c==s){res++;}
        } while(next_permutation(t.begin(),t.end()));
        printf("%d\n",res);
    }
    return 0;
}

C++: #include<bits/stdc++.h>

using namespace std;

set<vector<int>> res;

int n,k,s;
void search(vector<int> now, int m) {
    if(now.size() == k) {
        int sum=0;
        for(auto &e : now)
            sum += e;
        if(sum==s) res.insert(now);
        return;
    }
    for(int i=m+1; i<=n; i++) {
        vector<int> t(now);
        t.push_back(i);
        search(t, i);
    }
}

int main(void) {
    while(1) {
        cin>>n>>k>>s;
        if(!n) break;
        res.clear();
        search(vector<int>(), 0);
        cout<<res.size()<<endl;
    }
    return 0;
}

C++: #include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <cstring>
#include <iostream>
#include<algorithm>  
using namespace std;
int n,s,k;
int f[11][21][156]; 
int main()
{
 while(1)
  {
   scanf("%d%d%d",&n,&k,&s);
   if(n==0&&k==0&&s==0) break;
   memset(f,0,sizeof(f));
   for(int i=1;i<=n;i++)
    f[1][i][i]=1;
   for(int i=2;i<=k;i++)
    for(int j=1;j<=n;j++)
     for(int t=1;t<=s;t++)
      for(int p=1;p<j;p++)
       {
        if(t-j>=1)
         f[i][j][t]+=f[i-1][p][t-j];
       }
   int ans=0;
   for(int i=1;i<=n;i++)
    ans+=f[k][i][s];
   printf("%d\n",ans) ;
  }
 return 0;
}

C++: #include <iostream>
using namespace std;

int cnt;

void countSet(int n, int k, int s) {
    if (k == 1 && s == n) {
        cnt++;
    } else if (s > n) {
        for (int i = n - 1; i > 0; --i) {
            countSet(i, k - 1, s - n);
        }
    }
}

int main()
{
    int n, k, s;
    while (cin >> n >> k >> s, n) {
        cnt = 0;
        if (k == 1 && s <= n) {
            cnt = 1;
        } else {
            for (int i = n; i * k > s; --i) {
                countSet(i, k, s);
            }
        }
        cout << cnt << endl;
    }
    return 0;
}