program z13_23;
var
f:text;
a,i:integer;
begin
Assign (f,'input.txt');
reset(f);
While not EOF(f) do
begin
i:=1;
while not EOLN(f) do
begin
read(f,a);
if a mod 2 =0 then begin writeln(i); readln(f);break; end;
i:=i+1;
end;
end;
close(f);
End.