View Compilation Error

0_0_23343949_29978.cpp: In function 'int main()':
0_0_23343949_29978.cpp:6:21: error: 'scanf' was not declared in this scope
  while(scanf("%d",&n)!=EOF)
                     ^
0_0_23343949_29978.cpp:6:24: error: 'EOF' was not declared in this scope
  while(scanf("%d",&n)!=EOF)
                        ^
0_0_23343949_29978.cpp:8:11: error: 'getchar' was not declared in this scope
   getchar();
           ^
0_0_23343949_29978.cpp:11:10: error: 'gets' was not declared in this scope
    gets(a);
          ^
0_0_23343949_29978.cpp:25:22: error: 'printf' was not declared in this scope
        printf("yes\n");
                      ^
0_0_23343949_29978.cpp:29:17: error: 'printf' was not declared in this scope
    printf("no\n");
                 ^