function real paragontiko(input int m);
        real total;
        total = 1;
        for (int i = 1; i <= m; i++) begin
            total = total * i;
        end
        return total;
    endfunction

    initial begin
        int  N=-5;
        real sum, total_sum;



        if(N<=0) begin
            $display("Error, N should be >0",);
            $finish;
        end

        sum=0.0;
        total_sum = 0.0;
        for (int i=1; i<=N; i++) begin
            if(i%2==0) begin
                sum = 1.0/real'(i) - 1.0/paragontiko(i);
            end else begin
                sum = 1.0/real'(i) + 1.0/paragontiko(i);
            end
            $display("sum=%f",sum);
            total_sum = total_sum + sum;
        end

        $display("S=%f",total_sum);
    end