program PascalGuru;
uses crt;
label 1;
var m:array[1..50] of string;
    s:string;
    i,n:integer;
 
    procedure exchange(var a,b:char);
    var c:char;
    begin
    c:=a; a:=b; b:=c; end;
 
procedure perest(var s:string);
var i:integer;
begin
i:=0;
     while (i<length(s)-1) do begin
     i:=i+2;
     exchange(s[i-1],s[i]);
     end;
end;
{-------------------------------------------}
begin
write('N= '); readln(n);
clrscr;
writeln('Vvedite ',n,' strok (Zakancivaiucixsia "0")');
for i:=1 to n do
begin
1: write(i,') '); readln(s);
if s[length(s)]<>'0' then begin writeln('Vy vveli stroky, gde net v konce "0". Potorite vvod '); goto 1; end;
m[i]:=s;
 end;
 
clrscr;
writeln('Vy vveli: ');
for i:=1 to n do writeln(i,') ',m[i]);
 
for i:=1 to n do perest(m[i]);
 
 
writeln('Posle perestanovki: ');
for i:=1 to n do writeln(i,') ',m[i]);
 
 
readln;
end.