/in/foo.cc: In function 'void KMP()':
/in/foo.cc:63:42: warning: the address of 'fail' will never be NULL [-Waddress]
   63 |                 while ((fix << 1) > i && fail)fix = fail[fix];
      |                                          ^~~~
/in/foo.cc:28:8: note: 'fail' declared here
   28 | int T, fail[1000005], num[1000005];
      |        ^~~~