求一个不多于20位的整数*45的解。

var
st:string[20];
len,i,t:integer;
a:array [1..30] of integer;
begin
readln(st);
len:=length(st);
for i:=1 to len do a[i]:=ord(st[len-i+1])-48;
t:=0;
for i:=1 to len do
begin
a[i]:=a[i]*45+t;
t:=a[i] div 10;
a[i]:=a[i] mod 10;
end;
while t>0 do
begin
inc(len);
a[len]:=t mod 10;
t:=t div 10;
end;
for i:=len downto 1 do write(a[i]);
end.

谢谢