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#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

int main() {
    ifstream fin("input.txt");
    ofstream fout("output.txt");

    int n, m;
    fin >> n >> m;
    vector<vector<int>> dp(n, vector<int>(m, 1));
    for (int i = 1; i < n; i++)
        for (int j = 1; j < m; j++)
            dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
    fout << dp[n - 1][m - 1] << endl;

    fin.close();
    fout.close();
    return 0;
}