View Compilation Error

0_0_22713906_28906.cpp: In function 'int main()':
0_0_22713906_28906.cpp:31:19: error: 'scanf' was not declared in this scope
     scanf("%d", &T);
                   ^
0_0_22713906_28906.cpp:35:25: error: 'strlen' was not declared in this scope
         int n = strlen(s);
                         ^
0_0_22713906_28906.cpp:44:31: error: 'printf' was not declared in this scope
             printf("%d\n", ans);
                               ^