#include<stdio.h>
int main()
{
    int n;
    if(scanf("%d",&n)!=1){
        return 0;
    }
    if(n<0){
        printf("-1");
        return 0;
    }
    int sum=0;
    int current_expense;
    for(int i=0;i<n;i++){
        if(scanf("%d",&current_expense)==1){
            sum+=current_expense;
        }
        printf("%d",sum);
        return 0;
    }