View Compilation Error

0_0_37363621_3104.cpp: In function 'int main()':
0_0_37363621_3104.cpp:5:22: error: 'scanf' was not declared in this scope
    while(scanf("%s",a)!=EOF)
                      ^
0_0_37363621_3104.cpp:5:25: error: 'EOF' was not declared in this scope
    while(scanf("%s",a)!=EOF)
                         ^
0_0_37363621_3104.cpp:16:20: error: 'printf' was not declared in this scope
    printf("%c",a[i]);
                    ^
0_0_37363621_3104.cpp:20:15: error: 'printf' was not declared in this scope
    printf("\n");
               ^