using namespace std;

signed main(){ int n;cin>>n; vector v(n); for (int i=0;i<n;++i) cin>>v[i]; vectorisneighbor(1e5+5,0); vectorele(1e5+5,0); for(int i=0;i<n;++i){ ele[v[i]]+=1; } priority_queue<pair<int,int>>pq; for(int i=0;i<n;++i){ int sum=0; sum += v[i] + ele[v[i]-1]*(v[i]-1) + ele[v[i]+1]*(v[i]+1); pq.push({-sum,v[i]}); } int ans = 0; while(!pq.empty()){ pair<int,int> pii = pq.top(); pq.pop(); int curr = pii.second; if (isneighbor[curr]) continue; ans += curr; isneighbor[curr-1] = 1; isneighbor[curr+1] = 1; } cout<<ans<<'\n'; }