View Compilation Error

0_0_33701663_11827.cpp: In function 'int main()':
0_0_33701663_11827.cpp:4:18: error: 'scanf' was not declared in this scope
     scanf("%d",&n);
                  ^
0_0_33701663_11827.cpp:8:21: error: 'strlen' was not declared in this scope
         end=strlen(a)-1;
                     ^
0_0_33701663_11827.cpp:19:27: error: 'printf' was not declared in this scope
             printf("yes\n");
                           ^
0_0_33701663_11827.cpp:21:26: error: 'printf' was not declared in this scope
             printf("no\n");
                          ^