Correction BAC 2013 a 14h

program bac2013v14h;
uses wincrt;
var ch,n:integer;

procedure saisir (var ch:string);
var j:integer; trv:boolean;
begin
repeat
writeln('Donner une chaine');
readln(ch);
repeat
j:=j+1;
trv := (ch[j] in ['C','D','X','V','I','L','M']);
until((j= length(ch)) or (trv = false));
until(trv);
end;

procedure convertir(ch:string; var n:integer);
var i:integer;
begin
n:=0;
for i:= 1 to length(ch) do
begin
case ch[i] of
 'M': n:=n+1000;
 'C': n:=n+100;
 'D': n:=n+500;
 'L': n:=n+50;
 'X': n:=n+10;
 'V': n:=n+5;
 'I': n:=n+1;
end;
end;


begin
saisir(ch);
convertir(ch,n);
writeln('Le chiffre c''est: ',n);

end.