View Compilation Error

0_0_39628531_28613.cpp: In function 'long long int read()':
0_0_39628531_28613.cpp:23:52: error: 'getchar_unlocked' was not declared in this scope; did you mean '_getchar_nolock'?
   23 |         while(c>='0'&&c<='9')   now=now*10+c-'0',c=getchar_unlocked();
      |                                                    ^~~~~~~~~~~~~~~~
      |                                                    _getchar_nolock