/in/foo.cc: In function 'int ack(int, int)':
/in/foo.cc:6:8: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  if(a=0) return b+1;
        ^
/in/foo.cc:7:8: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  if(b=0) return ack(a-1,1);
        ^