import java.lang.Integer.max
fun main() = with(System.`in`.bufferedReader()){
val n = readLine().toInt()
val dp = IntArray(n+1){0}
val temp = readLine().split(" ").map{it.toInt()}
val list = IntArray(n+1)
for(i in 0 until temp.size){
list[i+1] = temp[i]
}
dp[1] = list[1]
for (i in 1..n) {
for(j in 1..i){
dp[i] = max(dp[i],dp[i-j]+list[j])
}
}
println(dp[n])
}