[tex]i=2<4[/tex] is true, so "Hello" is printed, then we increment [tex]i[/tex] by 1.
Now [tex]i=3[/tex] and [tex]3<4[/tex], so "Hello" gets printed again.
Next [tex]i=4[/tex], but [tex]4<4[/tex] is false, so the while loop is broken.
So, the loop only prints "Hello" twice.