/in/foo.c: In function 'main':
/in/foo.c:8:2: warning: 'k2' is used uninitialized in this function [-Wuninitialized]
  for(k1=0;k1<k2;k1++)
  ^~~
/in/foo.c:15:2: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized]
  printf("%d\n",y);
  ^~~~~~~~~~~~~~~~