합분해

#include <stdio.h>
#define mod 1000000000

int a[201][201] = { 0, };

int main() {
	//freopen("input.txt", "rt", stdin);
	int n, k;
	
	scanf("%d %d", &n, &k);
	for (int i = 1; i <= k; i++) {
		a[1][i] = i;
	}
	for (int i = 1; i <= n; i++) {
		a[i][1] = 1;
	}
	for (int i = 2; i <= n; i++) {
		for (int j = 2; j <= k; j++) {
			a[i][j] = (a[i - 1][j] + a[i][j - 1]) % mod;
		}
	}
	printf("%d\n", a[n][k] % mod);
	
	return 0;
}