/in/foo.cc: In function 'void build(int, int, int)':
/in/foo.cc:79:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     int mid=L+R>>1;
             ~^~
/in/foo.cc: In function 'node ask(int)':
/in/foo.cc:107:22: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     int mid=tree[k].l+tree[k].r>>1;
             ~~~~~~~~~^~~~~~~~~~
/in/foo.cc: In function 'void lian(int)':
/in/foo.cc:120:22: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     int mid=tree[k].l+tree[k].r>>1;
             ~~~~~~~~~^~~~~~~~~~