12 day 1

#include <cstdio>
int i,j,m,n,t;
long long f[6000][6000];
inline int min(int a,int b){
	return a<b?a:b;
}
int main(){
//	freopen("ticket.in","r",stdin);
//	freopen("ticket.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(i=1;i<=n;++i) f[i][0]=1;
	for(i=1;i<=n;++i){
		t=min(m,i);
		for(j=1;j<=t;++j){
			if(i==j){
				f[i][j]=f[i][j-1];
			}else{
				f[i][j]=f[i][j-1]+f[i-1][j];
			}
		}
	}
	printf("%lld\n",f[n][m]);
	return 0;
}