View Compilation Error

0_0_30008470_25709.cpp: In function 'int main()':
0_0_30008470_25709.cpp:5:18: error: 'scanf' was not declared in this scope
     scanf("%d",&n);
                  ^
0_0_30008470_25709.cpp:9:17: error: 'gets' was not declared in this scope
         gets(str);
                 ^
0_0_30008470_25709.cpp:19:31: error: 'printf' was not declared in this scope
             printf("%c",str[i]);
                               ^
0_0_30008470_25709.cpp:21:37: error: 'printf' was not declared in this scope
             printf("%d%c",cnt,str[i]);
                                     ^
0_0_30008470_25709.cpp:24:20: error: 'printf' was not declared in this scope
         printf("\n");
                    ^