#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000003

int main(){	
	
	int N;
	cin>>N;
	
	vector<long long> A(N);
	rep(i,N){
		cin>>A[i];
	}
	
	sort(A.begin(),A.end());
	
	map<long long,long long> mp;
	
	rep(i,A.size()){
		mp[A[i]] ++;
		if(mp.count(A[i]-1)){
			mp[A[i]+1] += mp[A[i]-1];
		}
	}
	
	long long ans = 0LL;
	for(auto a:mp){
		ans += a.second;
	}
	
	
	
	cout<<ans<<endl;
	
    return 0;
}