two.txt

本程序实现编译原理中

var n, m, fact, sum;
procedure factorial;
begin
    if m > 0 then
        begin
            fact := fact * m;
            m := m - 1;
            call factorial;
        end;
end;

begin
    read(n);
    sum := 0;
    while n > 0 do
        begin
            m := n;
            fact := 1;
            call factorial;
            sum  := sum + fact;
            n := n - 1;
        end;
    write(sum);
end.