#include<iostream>
using namespace std;
int main(){
    int n;
    cin>>n;
    if(n<0){
        cout<<"Invalid input";
        return 0;
    }
    int deposit,total 0;
    for(int i=0;i<n;i++){
        cin>>>deposit;
        if(deposit<0){
            cout<<"Invalid input";
            return 0;
        }
        total += deposit;
    }
    cout<<total;
    return 0;
}