/in/foo.cc: In function 'int init()':
/in/foo.cc:13:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'bool check(int, int)':
/in/foo.cc:20:14: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(a[num][i]&&b[i]!=color||!a[num][i]) 
     ~~~~~~~~~^~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:40:16: error: too few arguments to function 'void dfs(int, int)'
         dfs(n+1);
                ^
/in/foo.cc:28:6: note: declared here
 void dfs(int num,int color)
      ^~~
/in/foo.cc:39:13: warning: unused variable 'num' [-Wunused-variable]
         int num=n;
             ^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:46:6: error: too few arguments to function 'void dfs(int, int)'
  dfs();
      ^
/in/foo.cc:28:6: note: declared here
 void dfs(int num,int color)
      ^~~
/in/foo.cc: In function 'bool check(int, int)':
/in/foo.cc:27:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^