I can't imagine why you can't get AC?!?!?!?

Just look at my solution!!

below:
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program a1083;
var
st1:string;
s,s1,k,i:longint;
begin
     readln(st1);
     s:=0;
     for i:=1 to length(st1) do
         if st1[i]<>' ' then s:=s*10+ord(st1[i])-48 else break;
     k:=length(st1)-i;
     s1:=s;s:=1;
     repeat
           s:=s*s1;
           s1:=s1-k;
     until s1<=0;
     writeln(s);
end.