// #define _GLIBCXX_DEBUG // for STL debug (optional)
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <fstream>
#include <functional>
#include <bitset>
using namespace std;
using ll = long long int;
using int64 = long long int;
 
template<typename T> void chmax(T &a, T b) {a = max(a, b);}
template<typename T> void chmin(T &a, T b) {a = min(a, b);}
template<typename T> void chadd(T &a, T b) {a = a + b;}
 
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
const int INF = 1LL << 29;
const ll LONGINF = 1LL << 60;
const ll MOD = 1000000007LL;
 
int main() {
    int N; scanf("%d", &N);
    vector<ll> odd, even;
    for(int i=0; i<N; i++) {
        ll v; scanf("%lld", &v);
        if(v % 2) odd.emplace_back(v);
        else even.emplace_back(v);
    }

    sort(odd.begin(), odd.end());
    sort(even.begin(), even.end());
    vector<int> nxt_odd(odd.size(), 1), nxt_even(even.size(), 1);
    for(int i=(int)odd.size()-2; i>=0; i--) {
        if(odd[i+1] - odd[i] == 2) nxt_odd[i] = nxt_odd[i+1] + 1;
    }
    for(int i=(int)even.size()-2; i>=0; i--) {
        if(even[i+1] - even[i] == 2) nxt_even[i] = nxt_even[i+1] + 1;
    }

    ll ans = N;
    {
        int ie = 0;
        for(int io=0; io<(int)odd.size(); io++) {
            while(ie < (int)even.size() and odd[io] + 1 > even[ie]) ie++;
            if(ie >= (int)even.size()) continue;
            if(even[ie] != odd[io] + 1) continue;
            int len = nxt_even[ie];
            ans += len;
        }
    }
    {
        int io = 0;
        for(int ie=0; ie<(int)even.size(); ie++) {
            while(io < (int)odd.size() and even[ie] + 1 > odd[io]) io++;
            if(io >= (int)odd.size()) continue;
            if(odd[io] != even[ie] + 1) continue;
            int len = nxt_odd[io];
            ans += len;
        }
    }
    printf("%lld\n", ans);
    
    
    // 1 2 4 6 -> 3 4 6 -> 5 6 -> 7
    // 1 2 . 4 . 6
    // 2 3 . 5
    // 3 4 . 6
    return 0;
}