//#pragma comment(linker,"/STACK:1024000000,1024000000")

#include<iostream>

#include<cstdio>

#include<string>

#include<cstring>

#include<vector>

#include<cmath>

#include<queue>

#include<stack>

#include<map>

#include<set>

#include<algorithm>

#include <stack>

#include <ctime>

#include <iomanip>

using namespace std;

const int SZ=,INF=0x7FFFFFFF;

typedef long long lon;

lon num[SZ];

int main()

{

    std::ios::sync_with_stdio();

    //freopen("d:\\1.txt","r",stdin);

    int n;

    //for(;cin>>n,n;)

    {

        cin>>n;

        for(int i=;i<n;++i)

        {

            int tmp;

            cin>>tmp;

            ++num[tmp];

        }

        for(int i=;i<SZ;++i)

        {

            num[i+]+=num[i]/;

            num[i]=(num[i]&);

        }

//        for(int i=0;i<SZ;++i)

//        {

//            if(num[i])cout<<i<<" ";

//        }cout<<endl;

        int res=count(num,num+SZ,);

        cout<<res<<endl;

    }

    return ;

}