View Compilation Error

0_0_31889544_32407.cpp: In function 'int main()':
0_0_31889544_32407.cpp:12:12: error: expected primary-expression before 'long'
    cout << long long int(pow(3, length / 2 + 1) * pow(2, length / 2) + pow(2, length / 2))<<endl;
            ^
0_0_31889544_32407.cpp:14:12: error: expected primary-expression before 'long'
    cout << long long int (pow(3, length / 2)* pow(2, length / 2) + pow(2, length / 2))<<endl;
            ^