/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:63:8: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
  printf("%lld\n",ans);
  ~~~~~~^~~~~~~~~~~~~~