/in/foo.c: In function 'main':
/in/foo.c:8:9: warning: 'la' is used uninitialized in this function [-Wuninitialized]
  while(A[la]!='\0')
        ~^~~~
/in/foo.c:10:9: warning: 'lb' is used uninitialized in this function [-Wuninitialized]
  while(B[lb]!='\0')
        ~^~~~