View Compilation Error

0_0_27684659_32588.cpp: In function 'int main()':
0_0_27684659_32588.cpp:5:21: error: 'scanf' was not declared in this scope
  while(scanf("%d",&n)!=EOF)
                     ^
0_0_27684659_32588.cpp:5:24: error: 'EOF' was not declared in this scope
  while(scanf("%d",&n)!=EOF)
                        ^
0_0_27684659_32588.cpp:13:19: error: 'printf' was not declared in this scope
   printf("%d",a[n]);
                   ^