template<bool, int T, int F> struct If;
template<int T, int F>
struct If<true, T, F> {
    static const int value = T;
};
template<int T, int F>
struct If<false, T, F> {
    static const int value = F;
};

template<int L, int R, int, int N>
struct BinarySearch {
    static const int M = (L + R) / 2;
    static const int value = BinarySearch<
    If<(M * M >= N), M, R>::value,
    If<(M * M >= N), L, M>::value,
    R - L,
    N>::value;
};

template<int L, int R, int N>
struct BinarySearch<L, R, 1, N> {
    static const int value = R;
};

template<int L, int R, int N>
struct BinarySearch<L, R, 0, N> {
    static const int value = R;
};

template<int N>
struct Sqrt {
    static const int value = BinarySearch<0, N, N, N>::value;
};