/in/foo.cc: In function 'void build(int, int, int)':
/in/foo.cc:22:10: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int m=l+r>>1;
         ~^~
/in/foo.cc: In function 'int findkth(int, int, int, int)':
/in/foo.cc:32:9: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int m=l+r>>1;
        ~^~
/in/foo.cc: In function 'int main()':
/in/foo.cc:41:11: warning: unused variable 'j' [-Wunused-variable]
     int i,j,k;
           ^
/in/foo.cc:41:13: warning: unused variable 'k' [-Wunused-variable]
     int i,j,k;
             ^