#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 >> deposite;
        
        if(deposit < 0)
        {
            cout << "Invalid input";
            return 0;
        }
        total += deposit;
    }
    
    cout << total;
    return 0;
}