/in/foo.cc: In function 'int main()':
/in/foo.cc:10:19: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(r4==0||r100==0&&r400=0)
            ~~~~~~~^~~~~~
/in/foo.cc:10:26: error: lvalue required as left operand of assignment
  if(r4==0||r100==0&&r400=0)
                          ^