View Compilation Error

0_0_33394913_25152.cpp: In function 'int main()':
0_0_33394913_25152.cpp:15:20: error: 'scanf' was not declared in this scope
  scanf("%d", &tcase);
                    ^
0_0_33394913_25152.cpp:30:3: error: '__int64' was not declared in this scope
   __int64 ans = 0;
   ^
0_0_33394913_25152.cpp:52:5: error: 'ans' was not declared in this scope
     ans += 1LL * a[i] * (p * q);
     ^
0_0_33394913_25152.cpp:55:21: error: 'ans' was not declared in this scope
   printf("%I64d\n", ans);
                     ^
0_0_33394913_25152.cpp:55:24: error: 'printf' was not declared in this scope
   printf("%I64d\n", ans);
                        ^