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.