#include<bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define print(n) cout << n << endl;
int main(){
    int N;cin >> N;vector<int> A(N);
    rep(i,N)cin >> A[i];
    sort(A.begin(),A.end());
    int ans = 0;
    rep(i,N-1)if(A[i+1] != A[i] + 1)ans += A[i+1];
    ans += A[0];
    cout << ans << endl;
}