#include <iostream>
using namespace std;
int main()
{
    int n, countC=0, countN=0, sumC=0, sumN=0, x, buf;
    cin >> n;
    for(int i=0; i<n; i++){
        cin >> x;
        if (x % 2) {
            countC ++;
            sumC += x;
        }
        else
        {
            countN++;
            sumN += x;
        }
    }
    while (scanf("%1d", &x)) {
        if (x) {
            countN += countC;
            countC = 0;
            sumN += sumC/2;
            sumC = 0;
        }
        else {
            countC += countN;
            sumC += sumN+countN;
            sumC = 0;
            countC = 0;
        }
    }
    cout << sumC + sumN;
}