/in/foo.cc: In function 'int main()':
/in/foo.cc:21:27: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
 inline void writeln(ll x){if(x<0) x=-x,putchar('-');write(x);putchar('\n');}
                           ^~
/in/foo.cc:89:15: note: 'ans' was declared here
  int l=0,r=mx,ans;
               ^~~