#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
int h, n;
long long dp[31][31];
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
fill(&dp[0][0], &dp[30][30], 0);
cin >> h >> n;
for (int i = 0; i < 31; i++)
dp[0][i] = 1;
for (int i = 1; i < 31; i++) {
for (int j = i; j < 31; j++) {
dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
}
}
int answer = abs(h - n);
cout << dp[answer][answer];
return 0;
}