/in/foo.cc: In function 'int main()':
/in/foo.cc:7:5: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
  a=m<=a<=n;
    ~^~~
/in/foo.cc:8:11: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(a%4==0&&a%100!=0||a%400==0)
     ~~~~~~^~~~~~~~~~
/in/foo.cc:7:5: warning: 'a' is used uninitialized in this function [-Wuninitialized]
  a=m<=a<=n;
    ~^~~