program odinak_v_4zn_ch;
var x,x1,x2,x3,x4:Integer;
begin
read(x);
x4:=x mod 10;
x3:=x mod 100 div 10;
x2:=x mod 1000 div 100;
x1:=x div 1000;
if(x1=x2)or(x1=x3)or(x1=x4)or(x2=x3)or(x2=x4)or(x3=x4)
then
write('yes')
else
write('no')
end.
program odinak_v_4zn_ch;
var x,x1,x2,x3,x4:Integer;
begin
read(x);
x4:=x mod 10;
x3:=x mod 100 div 10;
x2:=x mod 1000 div 100;
x1:=x div 1000;
if(x1=x2)or(x1=x3)or(x1=x4)or(x2=x3)or(x2=x4)or(x3=x4)
then
write('yes')
else
write('no')
end.