uses crt;
var n,tong,dem:longint;
begin
clrscr;
write('n=');readln(n);
tong:=2; dem:=2;
while tong*2<=n do begin tong:=tong*2; inc(dem); end;
while tong<n do begin inc(tong); inc(dem); end;
write('So lan len bang it nhat la: ');
if n=1 then write(1) else write(dem);
readln
end.
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Test: