TTRAVEL - Time Travel

Tác giả: flashmt

Ngôn ngữ: Pascal

uses math;
const fi='';
      fo='';
      maxn=80010;
var n,i,x:longint;
    c:char;
    a,d,p:array[-1..maxn] of longint;

begin
     assign(input,fi); reset(input);
     assign(output,fo); rewrite(output);
     readln(n);
     d[0]:=-1;
     for i:=1 to n do
     begin
          read(c);
          if c='a' then
          begin
               d[i]:=p[i-1];
               p[i]:=i;
               read(a[i]);
          end;
          if c='s' then
          begin
               p[i]:=d[i-1];
               d[i]:=d[d[i-1]];
          end;
          if c='t' then
          begin
               read(x);
               p[i]:=p[x-1];
               d[i]:=d[x-1];
          end;
          readln;
     end;
     for i:=1 to n do
         if a[p[i]]>0 then writeln(a[p[i]])
         else writeln(-1);
     close(input); close(output);
end.

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