/in/foo.cc: In function 'void m_sort(int, int)':
/in/foo.cc:14:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l+r>>1;
          ~^~
/in/foo.cc:18:17: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(y>r||x<=mid&&a[x]<=a[y])b[i]=a[x++];
           ~~~~~~^~~~~~~~~~~~