View Compilation Error

0_0_17766062_7211.cpp: In function 'int main()':
0_0_17766062_7211.cpp:54:19: error: 'scanf' was not declared in this scope
     scanf("%d", &T);
                   ^
0_0_17766062_7211.cpp:68:25: error: 'printf' was not declared in this scope
             printf("0\n");
                         ^
0_0_17766062_7211.cpp:102:47: error: 'printf' was not declared in this scope
         printf("%d\n", (n - 1) * 2 - (len + 1));
                                               ^