#include <stdio.h>

int main() {
    int n,key,sum = 0;
    scanf("%d",&n);
    int arr[n],x[n];
    for(int i=0;i<n;i++){
        scanf("%d",&arr[i]);
    }
    scanf("%d",&key);
    for(int i=0;i<key;i++){
        sum += arr[i+1];
        x[0] = sum
    }
    printf("%d",x[0]);
}