View Compilation Error

0_0_20381410_3961.cpp: In function 'void solve()':
0_0_20381410_3961.cpp:13:49: error: 'fgets_unlocked' was not declared in this scope
         fgets_unlocked(line, sizeof(line), stdin);
                                                 ^
0_0_20381410_3961.cpp:24:39: error: 'fgets_unlocked' was not declared in this scope
     fgets_unlocked(s, sizeof(s), stdin);
                                       ^