#include <vector>
#include <list>
#include <iostream>

using namespace std;

bool canCross(vector<int>& stones)
{
	int n=stones.size();
	if(n==1)
	{
		if(stones[0]==0) return true;
		else return false;
	}
	if(stones[0]!=0 || stones[1]!=1) return false;
	int bomb=0;
	list<int> gaps;
	for(int i=0; i<n-1; ++i)
	{
		gaps.push_back(stones[i+1]-stones[i]);
	}

	for(auto i=gaps.begin(); i!=gaps.end(); ++i)
	{
		while(bomb>0)
		{
			--i;
			--bomb;
		}
		auto i_next=i;
		++i_next;
		auto i_prev=i;
		--i_prev;
		if(i_next==gaps.end()) return true;
		int diff=(*i_next)-(*i);
		if(diff>=-1 && diff<=1) continue;
		if(diff>0)
		{
			if(i_prev==gaps.begin() || i==gaps.begin()) return false;
			(*i)=(*i)+(*i_prev);
			gaps.erase(i_prev);
			bomb=2;
		}
		else
		{
			if((*i_prev)<(*i))
			{
				auto i_next_next=i_next;
				++i_next_next;
				if(i_next_next==gaps.end()) return false;
				(*i_next)=(*i_next)+(*i_next_next);
				gaps.erase(i_next_next);
				bomb=1;
			}
			else
			{
				if(i_next==gaps.end()) return false;
				(*i)=(*i)+(*i_next);
				gaps.erase(i_next);
				--i;
				bomb=1;
			}
		}
	}
	return true;
}

int main()
{
	vector<int> input={0,1,3,6,10,13,15,16,19,21,25};
	vector<int> input2={0,1,3,5,6,8,12,17};
	vector<int> input3={0,1,2,3,4,8,9,11};
	cout << canCross(input) << endl;
	cout << canCross(input2) << endl;
	cout << canCross(input3) << endl;
	return 0;
}