/in/foo.cc: In function 'bool check1()':
/in/foo.cc:18:6: warning: unused variable 'k' [-Wunused-variable]
  int k = 0, now, nowa, nowb, nowc;
      ^
/in/foo.cc: In function 'void check()':
/in/foo.cc:5:19: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
 #define REP(i, n) for(int i = 1; i <= n; i ++)
                   ^
/in/foo.cc:36:2: note: in expansion of macro 'REP'
  REP(i, n) printf("%d ", num[i]); puts(""); exit(0);
  ^~~
/in/foo.cc:36:35: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
  REP(i, n) printf("%d ", num[i]); puts(""); exit(0);
                                   ^~~~