View Compilation Error

0_0_21778818_7049.cpp: In function 'int main(int, char**)':
0_0_21778818_7049.cpp:17:5: error: incomplete type 'std::ios_base' used in nested name specifier
     ios_base::sync_with_stdio(false);
     ^
0_0_21778818_7049.cpp:19:5: error: 'cin' was not declared in this scope
     cin >> cases;
     ^