не шарю Информатика 8 класса

 Program esep;
var i,j,k,n,sum:integer;
 input,output:text;
a:array[1..100] of integer;
flag:boolean;
begin flag:=false;
Assign(Input,'d.in');
reset(input);
readln(input,n);
assign(output, 'd.out');
rewrite(output);
writeln('Input elements');
readln (n);
for i:=1 to n do read(a[i]);
for i:=1 to n do 
for j:=1 to n do 
for k:=1 to n do 
if (i<>j) and (j<>k) and (i<>k) then
 if a[i]+a[j]+a[k]=0
then
begin
writeln (output,'Yes');
flag:=true;
halt;
end;
if flag=false then writeln(output,'No');
close(input);
close(output);
end.

Var i,j,k,n,sum:integer;
 input,output:text;
a:array[1..100] of integer;
flag:boolean;
begin flag:=false;
Assign(Input,'d.in');
reset(input);
readln(input,n);
assign(output, 'd.out');
rewrite(output);
writeln('Input elements');
readln (n);
for i:=1 to n do read(a[i]);
for i:=1 to n do 
for j:=1 to n do 
for k:=1 to n do 
if (i<>j) and (j<>k) and (i<>k) then
 if a[i]+a[j]+a[k]=0 
then
begin
writeln (output,'Yes');
flag:=true;
halt;
end;
if flag=false then writeln(output,'No');
close(input);
close(output);
end.