View Compilation Error

0_0_37990708_21770.cpp: In function 'int main()':
0_0_37990708_21770.cpp:6:24: error: 'scanf' was not declared in this scope
     while(scanf("%d",&a) != EOF)
                        ^
0_0_37990708_21770.cpp:6:29: error: 'EOF' was not declared in this scope
     while(scanf("%d",&a) != EOF)
                             ^
0_0_37990708_21770.cpp:19:31: error: 'printf' was not declared in this scope
             printf("%d\n",s[i]);
                               ^
0_0_37990708_21770.cpp:21:20: error: 'printf' was not declared in this scope
         printf("\n");
                    ^