#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<iostream>
#include <algorithm>
#include<cstdint>
#include<cstddef>
#include<vector>
//#include<atcoder/all>
//using namespace atcoder;
using namespace std;
using i32 = int_fast32_t;
using i64 = int_fast64_t;
using usize = uint_fast64_t;
#define rep(i, n) for (i64 i = 0; i < (i64)(n); ++i)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
using P = pair<i64,i64>;
void solve(){
}
int main(){
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    i64 n;
    cin >> n;
    vector<i64> a(n);
    rep(i,n)cin >> a[i];
    sort(all(a));
    i64 cnt = 1;
    rep(i,n - 1){
        if(a[i] + 1 >= a[i + 1])cnt++;
    }
    cout << cnt << endl;
}