#include <iostream>

template<unsigned long long n, int base = 8>
struct binary {
    enum {
        value = (binary<n / base>::value << 1) + (n % base == 1 ? 1 : 0)
    };
};

template<>
struct binary<0> {
    enum {
        value = 0
    };
};

#define BIN(n) binary<0 ## n ## ul>::value

int main()
{
    std::cout << BIN(1101001) << std::endl; // => 105
    std::cout << BIN(1111111111111111111111) << std::endl; // => 4194303
    return 0;
}