foo.cc: In function 'int main()':
foo.cc:47:19: warning: suggest parentheses around '+' in operand of '&' [-Wparentheses]
             if ((i+j&1)==0){
                  ~^~
foo.cc:50:30: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
                     int mid=l+r>>1;
                             ~^~

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