View Compilation Error

0_0_22850417_20647.cpp: In function 'int main()':
0_0_22850417_20647.cpp:5:23: error: 'scanf' was not declared in this scope
  while(scanf("%lld",&n)!=EOF)
                       ^
0_0_22850417_20647.cpp:5:26: error: 'EOF' was not declared in this scope
  while(scanf("%lld",&n)!=EOF)
                          ^
0_0_22850417_20647.cpp:11:20: error: 'printf' was not declared in this scope
    printf("first\n");
                    ^
0_0_22850417_20647.cpp:15:21: error: 'printf' was not declared in this scope
    printf("second\n");
                     ^
0_0_22850417_20647.cpp:17:20: error: 'printf' was not declared in this scope
    printf("first\n");
                    ^