/in/foo.cc: In function 'void Update(int, int, int, int, int, int)':
/in/foo.cc:85:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid = head+tail >> 1;
            ~~~~^~~~~
/in/foo.cc: In function 'seg Query(int, int, int, int, int)':
/in/foo.cc:95:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid = head+tail >> 1;
            ~~~~^~~~~
/in/foo.cc:92:6: warning: unused variable 'ans' [-Wunused-variable]
  int ans=0;
      ^~~
/in/foo.cc: In function 'void Check(int, int, int)':
/in/foo.cc:149:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid = head+tail >> 1;
            ~~~~^~~~~