/in/foo.cc: In function 'int main()':
/in/foo.cc:34:9: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
    mid=L+R>>1;//cout<<"L="<<L<<" R="<<R<<endl;
        ~^~
/in/foo.cc:38:8: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<res<<endl;
        ^~~