public int uniquePaths(int m, int n) {

        int[][] paths = new int[m][n];

        for (int i=0; i<m; i++) {
            for (int j=0; j<n; j++) {
                if (i==0 || j==0) {
                    paths[i][j] = 1;
                } else {
                    paths[i][j] = paths[i-1][j] + paths[i][j-1];
                }
            }
        }
        return paths[m-1][n-1];
    }