#include <map>
#include <ctime>
#include <cmath>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define F(i,j,k) for (int i=j;i<=k;++i)
#define D(i,j,k) for (int i=j;i>=k;--i)

class SRMCards{
	public:
	int maxTurns(vector <int> cards)
	{
		sort(cards.begin(),cards.end());
		int cnt=1,ans=0;
		for (int i=1;i<cards.size();++i)
		{
			if (cards[i]==cards[i-1]+1) cnt++;
			else
			{
				ans+=(cnt+1)/2;
				cnt=1;
			}
		}
		ans+=(cnt+1)/2;
		return ans;
	}
};