View Compilation Error

0_0_31200731_19558.cpp: In function 'int main()':
0_0_31200731_19558.cpp:8:22: error: 'scanf' was not declared in this scope
 while (scanf("%d", &n) != EOF)
                      ^
0_0_31200731_19558.cpp:8:27: error: 'EOF' was not declared in this scope
 while (scanf("%d", &n) != EOF)
                           ^
0_0_31200731_19558.cpp:34:19: error: 'printf' was not declared in this scope
 printf("%s\n",a[m]);
                   ^