Correction BAC 2013 a 11h

program bac2013v11;
uses wincrt;
var i,e,n:integer; ch:string;  trv1,trv2:boolean; a,x:longint;
procedure saisir(var n:integer);
begin
repeat
writeln('Donner n');
readln(n);
until(n>=10);
end;

procedure inverse (var ch:string);
var i,j:integer;
procedure permut (var x,y:char);
var aux:char;
begin
aux := x;
x := y;
y := aux;
end;

begin
i:=0;
j:=length(ch);
repeat
i:=i+1;
permut(ch[i],ch[j]);
j:=j-1;
until(j=i);
end;

function pali (var ch:string):boolean;
var debut,n:integer; trv:boolean;
begin
debut:=1;
n:= length(ch);
repeat
debut:=debut+1;
n:=n-1;

until((debut=n) or (ch[n] <> ch[debut]));
if (ch[n] <> ch[debut]) then trv:=false
else trv:=true;

pali:= trv;
end;

begin

saisir(n);
a:=n;
i:=0;
repeat
i:=i+1;
str(a,ch);
inverse(ch);
val(ch,x,e);
a:=a+x;
str(a,ch);
trv1:=((pali(ch)) and (i<=10));
trv2:=((pali(ch)=false) and (i=11));
until(trv1 or trv2);
if (trv1) then writeln('Cette suite est palindromique')
else if(trv2) then writeln('Le calcul de 11 termes ne donne pas une suite palidromique pour ce nombre.')


end.