var s,s1,s2:string;
max,i,j:integer;
c:char;
begin
Writeln('Stroka simvolov:');
Readln(s);
s1:=''; s2:=''; i:=1; j:=1; max:=0;
repeat
c:=s[i];
s1:=s1+c;
Inc(i);
While s[i]=c do
begin
s1:=s1+c;
Inc(j);
Inc(i);
end;
if j>max then
begin
max:=j;
s2:=s1;
end;
s1:='';
j:=1;
until i> Length(s);
Writeln;
Writeln(s2);
Readln;
end.