Hi there!

#define SZ(a) (ll)a.size()
#define FOR(i,a,b) for (ll i=(ll)a; i<=(ll)b; i++)
#define f first
#define mp make_pair
#define s second
#define p pair
#define all(C) C.begin(), C.end()

template<typename T> istream& operator>>(istream& in, vector<T>& a) {for(auto &x : a) in >> x; return in;};
template<typename T> ostream& operator<<(ostream& out, vector<T>& a) {for(auto &x : a) out << x << ' '; return out;};

vector<int> a(10);
cin >> a;
cout << a << endl;

10 is just a random number. It works for any size of the vector.

template<typename T1, typename T2> ostream& operator<<(ostream& out, const p<T1, T2>& x) {return out << x.f << ' ' << x.s;}
template<typename T1, typename T2> istream& operator>>(istream& in, p<T1, T2>& x) {return in >> x.f >> x.s;}

pair<int, int> a;
cin >> a;
cout << a;

template<typename T> using ordered_set = tree<T, null_type,less<T>, rb_tree_tag,tree_order_statistics_node_update>;
template<typename T> using ordered_multiset = tree<T, null_type,less_equal<T>, rb_tree_tag,tree_order_statistics_node_update>;

ordered_set<int> OS;
ordered_multiset<int> OMS;

template<typename T> using matrix = vector<vector<T> >;
template<typename T> using rubik = vector<vector<vector<T> > >;

rubik<int> a; // instead of vector<vector<vector<int> > > a;

template<typename T> void Unique(T &a) {a.erase(unique(a.begin(), a.end()), a.end());}

vector<int> a;
Unique(a);

ll powermod(ll a, ll b, ll m)
{
	if (b == 0) return 1;
	ull k = powermod(a, b / 2, m);
	k = k * k;
	k %= m;
	if (b & 1) k = (k * a) % m;
	return k;
}

// Prime test for large numbers

bool isPrime(ull n, int iter = 5) 
{
    if (n < 4) return n == 2 || n == 3;
	if (n % 2 == 0 || n % 3 == 0) return false;
    for (int i = 0; i < iter; i++) 
	{
        ull a = 2 + rand() % (n - 3);
        if (powermod(a, n - 1, n) != 1) return false;
    }
    return true;
}

multiset<ll> LIS(vector<ll> A)
{
	ll a = A.size();
	multiset<ll> S;
	multiset<ll>::iterator it;
	FOR(i, 0, a - 1)
	{
		S.insert(A[i]);
		it = S.upper_bound(A[i]);
		if (it != S.end()) S.erase(it);
	}
	return S;
}

multiset<ll> LSIS(vector<ll> A) // a.k.a Longest Strictly Increasing Sequence
{
	ll a = A.size();
	multiset<ll> S;
	multiset<ll>::iterator it;
	FOR(i, 0, a - 1)
	{
		S.insert(A[i]);
		it = S.lower_bound(A[i]);
		it++;
		if (it != S.end()) S.erase(it);
	}
	return S;
}