Intervals Handling

map<int, int> active;

void init()
{
	active[-1] = -1;
	active[2e9] = 2e9;
	active[1] = n;
}

void add(int L, int R) //Always remove [L, R] before adding
{
	active[L]=R;
	ans+=R-L+1;
}

void remove(int L, int R)
{
	int removed=0;
	auto it = active.lower_bound(L);
	it--;
	if(it->second>=L)
	{
		active[L] = it->second;
		it->second = L-1;
	}
	it++;
	while(it->first <= R)
	{
		if(it->second > R)
		{
			removed+=R + 1 - it->first;
			active[R+1] = it->second;
		}
		else
			removed+= it->second - it->first + 1;
		auto it2=it;
		it++;
		active.erase(it2);
	}
	ans-=removed;
}

//Problem 1: https://codeforces.com/contest/915/problem/E
//Solution 1: https://codeforces.com/contest/915/submission/40028187

//Problem 2 (with sets): https://codeforces.com/contest/899/problem/E
//Solution 2: https://codeforces.com/contest/899/submission/45963607