View Compilation Error

0_0_31426277_31578.cpp: In function 'int main()':
0_0_31426277_31578.cpp:10:23: error: 'scanf' was not declared in this scope
  while(scanf("%d",&num)!=EOF)
                       ^
0_0_31426277_31578.cpp:10:26: error: 'EOF' was not declared in this scope
  while(scanf("%d",&num)!=EOF)
                          ^
0_0_31426277_31578.cpp:12:28: error: 'printf' was not declared in this scope
   printf("%I64d\n",arr[num]);
                            ^