View Compilation Error

0_0_16724945_7375.cpp: In function 'int main()':
0_0_16724945_7375.cpp:6:17: error: 'scanf' was not declared in this scope
  scanf("%d\n",&n);
                 ^
0_0_16724945_7375.cpp:9:9: error: 'gets' was not declared in this scope
   gets(a);
         ^
0_0_16724945_7375.cpp:22:25: error: 'printf' was not declared in this scope
      printf("%c",s+'A'-1);
                         ^
0_0_16724945_7375.cpp:28:25: error: 'printf' was not declared in this scope
      printf("%c",s+'A'-1);
                         ^
0_0_16724945_7375.cpp:35:15: error: 'printf' was not declared in this scope
     printf(" ");
               ^
0_0_16724945_7375.cpp:37:14: error: 'printf' was not declared in this scope
   printf("\n");
              ^