//& для целых переменных
int bit_and_for_int_f1(unsigned long a, unsigned long b) {
    unsigned long c = a & b;
    //cout << c << endl;
    return c;
}

//& для целых переменных без оператора &
int bit_and_for_int_f2(unsigned long a, unsigned long b) {

    bitset <64> number_one(a);
    //cout << number_one.to_ulong() << " = " << number_one << endl;
    bitset <64> number_two(b);
    //cout << number_two.to_ulong() << " = " << number_two << endl;
    bitset <64> number;
    for (int i = 63; i >= 0; i--) {
        if (number_one[i] == 1) {
            if (number_two[i] == 1) {
                number[i] = 1;
            }
            else {
                number[i] = 0;
            }
        }
        else {
            if (number_two[i] == 1) {
                number[i] = 0;
            }
            else {
                number[i] = 0;
            }
        }
    }
    //cout << endl;
    //cout << number.to_ulong() << " = " << number;
    return number.to_ulong();
}

//тест & для целых переменных
void can_bit_and() {
    for (int i = 0; i < 1000000; i++) {
        assert(bit_and_for_int_f1(i, i + 2) == bit_and_for_int_f2(i, i + 2));
    }
}