Read QR code without advertising

Many free programs read the QR code but have advertising banners, or are unstable or complete the encoding in several steps. The problem is: there are too many of them.

Iphone reads the QR code directly, so you don't need to install anything.
 

Android needs the program instead.

The procedure is very simple.
 
On Google Play search QR Code Reader / no ads
 
Install.
 
It has no advertising and is the fastest.