optimization - Which variable should be optimize in following C code -

If your compiler actually optimizes the access time of two registers variables per function, then the following program has two variables The best ones can be made in register variables?

  Zero main (zero) {int i, j, k, m; Do {printf ("enter value"); Scanf (a ????% d, & amp; i); Meter = 0; For (k = 0; k & lt; 100; k ++) m = k + m; } While (i> gt; 0); }   
 Please remember if there is a mistake ...   
 
 
 Definitely not  j  because it is never used.  i  No, as you are using the operator's address to write to that address, which means read it back to memory after writing it by  scanf  should go. It only leaves  k  and  m .