foo.cc: In function 'void update(int)':
foo.cc:23:37: warning: statement has no effect [-Wunused-value]
  if(!cov[x<<1]&&!cov[x<<1|1]) cov[x]==0;
                               ~~~~~~^~~
foo.cc: In function 'void cover(int, int, int, int, int)':
foo.cc:38:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l+r>>1;
          ~^~
foo.cc: In function 'int query(int, int, int, int, int)':
foo.cc:46:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l+r>>1;
          ~^~

自豪的采用jd5进行评测(github.com/masnn/jd5)