View Compilation Error

0_0_11798592_29367.cpp: In function `int fast_read_int()':
0_0_11798592_29367.cpp:140: error: `getchar_unlocked' undeclared (first use this function)
0_0_11798592_29367.cpp:140: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_11798592_29367.cpp: In function `char fast_read_char()':
0_0_11798592_29367.cpp:156: error: `getchar_unlocked' undeclared (first use this function)