// No.1686 Geschenkt
package main

import (
	"fmt"
	"sort"
)

func main() {
	var n int
	fmt.Scan(&n)

	a := make([]int, n)
	for i := 0; i < n; i++ {
		fmt.Scan(&a[i])
	}

	sort.Ints(a)

	ans := a[0]
	for j := len(a) - 1; j > 0; j-- {
		if a[j] != a[j-1]+1 {
			ans += a[j]
		}
	}
	fmt.Println(ans)
}