Left Of The Star

int a = 1, b = 2;

const int* p = &a;
int* const q = &a;
const int* const r = &a;

p = &b;    // line 1
*p = 5;    // line 2
q = &b;    // line 3
*q = 5;    // line 4
r = &b;    // line 5
*r = 5;    // line 6

Select every line that fails to compile.