/in/foo.cc: In function 'int main()':
/in/foo.cc:45:49: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
         if ((x1+y1 < x2+y2) || (x1+y1 == x2+y2) && (x1*a+y1*b < x2*a+y2*b))
                                ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~