/in/foo.c: In function 'main':
/in/foo.c:28:2: warning: iteration 4 invokes undefined behavior [-Waggressive-loop-optimizations]
  printf("%d ",a[i]);
  ^~~~~~~~~~~~~~~~~~
/in/foo.c:27:2: note: within this loop
  for(i=1;i<=5;i++)
  ^~~
/in/foo.c:10:8: warning: array subscript is above array bounds [-Warray-bounds]
  a[5]=a[5]+a[1];
       ~^~~
/in/foo.c:24:3: warning: array subscript is above array bounds [-Warray-bounds]
  a[5]=a[5]/3;
  ~^~~