#include <iostream>
#include <vector>
using namespace std;
void restructArray(vector<int>& arr, vector<vector<int>>& query) {
    int size = arr[0];
        vector<int> data(arr.begin() + 1, arr.end());
        for(const auto& q : query) {
        int position = size * (q[0] - 1) + (q[1] - 1);
        cout << data[position] << endl;
    }
}

#include <bits/stdc++.h>
using namespace std;

int main(){
    int P;
    cin >> P;
    while(P--){
        string path;
        cin >> path;
        int horizontal = 0, vertical = 0;
        for(char direction : path){
            switch(direction){
                case 'N': vertical++; break;
                case 'S': vertical--; break;
                case 'E': horizontal++; break;
                case 'W': horizontal--; break;
            }
        }
        if(horizontal == 0 && vertical == 0){
            cout << "true\n";
        }
        else{
            cout << "false\n";
        }
    }
}

#include <iostream>
#include <vector>
using namespace std;
long long solve(int a, int b, vector<int>& c, vector<int>& d) {
    vector<long long> e(a, 0); 
    int f = 0;  
    while (f < b) {
        long long g = e[0];
        long long h = g;     
        int i = 0; 
        while (i < a) {
            if (h < e[i]) {
                long long delay = e[i] - h; 
                g += delay;                 
                h = e[i];                  
            }
            h += (long long)c[i] * d[f]; 
            i++;
        }
        h = g;  
        i = 0; 
        while (i < a) {
            long long workTime = (long long)c[i] * d[f];
            e[i] = h + workTime; 
            h += workTime;       
            i++;
        }
        f++;  
    }
    return e[a - 1];  
}

MOD = 10**9 + 7
def countSameBitNumbers(N):
    k, set_bits = N.bit_length(), bin(N).count('1')

    def combination(n, k):
        if k > n: return 0
        if k == 0 or k == n: return 1
        k = min(k, n - k)
        result = 1
        for i in range(1, k + 1):
            result = result * (n - i + 1) // i
        return result

    return (combination(k, set_bits) - 1) % MOD

def pf_exp(c):
    d = {}
    a = 2
    while a * a <= c:
        while (c % a) == 0:
            if a in d:
                d[a] += 1
            else:
                d[a] = 1
            c //= a
        a += 1
    if c > 1:
        d[c] = 1
    return d
def calc_sum(a, b):
    if not a:
        return -1
    d = pf_exp(b)
    e = 0
    f = False
    for g, h in d.items():
        if g < len(a):
            e += h * a[g]
            f = True
    return e if f else 0
n = int(input().strip())
a = list(map(int, input().strip().split()))
b = int(input().strip())
result = calc_sum(a, b)
print(result)

#include <iostream>
#include <string>
#include <sstream>
#include <vector>
bool isValidSegment(string &segment) {
    if (segment.empty() || segment.size() > 3) {
        return false;
    }
        for (char ch : segment) {
        if (!isdigit(ch)) {
            return false;
        }
    }
    
    int num = stoi(segment);
        if (num < 0 || num > 255) {
        return false;
    }
    if (segment.size() > 1 && segment[0] == '0') {
        return false;
    }

    return true;
}

bool isValidIPAddress(string &ip) {
  stringstream ss(ip);
   string segment;
  vector<string> segments;
    
    while (getline(ss, segment, '.')) {
        segments.push_back(segment);
    }

    if (segments.size() != 4) {
        return false;
    }
        for (string &seg : segments) {
        if (!isValidSegment(seg)) {
            return false;
        }
    }
    
    return true;
}
int main() {
string ip;
  cin >> ip;
    
    if (isValidIPAddress(ip)) {
      cout << "true" << std::endl;
    } else {
        cout << "false" << std::endl;
    }

    return 0;
}