/in/foo.cc: In function 'int main()':
/in/foo.cc:30:15: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(left>=11 && left-right>=2 || right>=11 && right-left>=2 )
      ~~~~~~~~~^~~~~~~~~~~~~~~~
/in/foo.cc:52:15: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(left>=21 && left-right>=2 ||right>=21 && right-left>=2)
      ~~~~~~~~~^~~~~~~~~~~~~~~~