/in/foo.cc: In function 'int main()':
/in/foo.cc:60:20: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   if(check(mid = l + r >> 1)) ans = mid,r = mid - 1;
                  ~~^~~
/in/foo.cc:57:24: warning: variable 'ans' set but not used [-Wunused-but-set-variable]
  ll l = 1,r = k<<3,mid,ans;
                        ^~~