#include <cstdio>
#include <vector>
using std::vector;

int main(){
	int n;
	scanf("%d",&n);
	vector<int> a(n);
	for(int i = 0; i < n; i++) scanf("%d",&a[i]);
	int ans = 0;
	for(int i = 0; i < n; i++){
		int find = 0;
		for(int j = 0; j < n; j++) if(a[j]+1 == a[i]) find = 1;
		if(!find) ans += a[i];
	}
	printf("%d\n",ans);
	return 0;
}