#include<iostream> #include<string> #include<cstdio> #include<vector> #include<cmath> #include<algorithm> #include<functional> #include<iomanip> #include<queue> #include<ciso646> #include<random> #include<map> #include<set> #include<complex> #include<bitset> #include<stack> #include<unordered_map> #include<utility> #include<tuple> #include<cassert> using namespace std; typedef long long ll; typedef unsigned int ui; const ll mod = 1000000007; const ll INF = (ll)1000000007 * 1000000007; typedef pair<int, int> P; #define stop char nyaa;cin>>nyaa; #define rep(i,n) for(int i=0;i<n;i++) #define per(i,n) for(int i=n-1;i>=0;i--) #define Rep(i,sta,n) for(int i=sta;i<n;i++) #define Per(i,sta,n) for(int i=n-1;i>=sta;i--) #define rep1(i,n) for(int i=1;i<=n;i++) #define per1(i,n) for(int i=n;i>=1;i--) #define Rep1(i,sta,n) for(int i=sta;i<=n;i++) typedef long double ld; const ld eps = 1e-8; const ld pi = acos(-1.0); typedef pair<ll, ll> LP; int dx[4]={1,-1,0,0}; int dy[4]={0,0,1,-1}; template<class T>bool chmax(T &a, const T &b) {if(a<b){a=b;return 1;}return 0;} template<class T>bool chmin(T &a, const T &b) {if(b<a){a=b;return 1;}return 0;} int n; ll a[200010]; map<ll,ll> dp; void solve(){ cin >> n; rep(i,n) cin >> a[i]; sort(a,a+n); ll ans=0; rep(i,n){ ans+=1; dp[a[i]]+=1; ans+=dp[a[i]-1]; dp[a[i]+1]+=dp[a[i]-1]; } cout << ans << endl; } int main(){ ios::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(50); solve(); }