View Compilation Error

0_0_23213108_27991.cpp: In function 'void fastread(int*)':
0_0_23213108_27991.cpp:6:24: error: 'getchar_unlocked' was not declared in this scope
     c=getchar_unlocked();}
                        ^
0_0_23213108_27991.cpp:10:24: error: 'getchar_unlocked' was not declared in this scope
     c=getchar_unlocked();
                        ^