View Compilation Error

0_0_38388823_25694.cpp: In function 'int main()':
0_0_38388823_25694.cpp:9:18: error: 'scanf' was not declared in this scope
     scanf("%d",&n);
                  ^
0_0_38388823_25694.cpp:13:32: error: 'printf' was not declared in this scope
         printf("%lld\n", a[b-x]);
                                ^