c1

#include <iostream>

using namespace std;

long long gcdex(long long a, long long b, long long &x, long long &y) {
    if (a == 0) {
        x = 0;
        y = 1;
        return b;
    }
    long long x1, y1;
    long long d = gcdex(b % a, a, x1, y1);
    x = y1 - (b / a) * x1;
    y = x1;
    return d;
}

long long inv(long long a, long long m) {
    long long x, y;
    long long g = gcdex(a, m, x, y);
    if (g != 1) {
        return 0;
    }
    x = (x % m + m) % m;
    return x;
}

long long m, n = 0, b[50], a[15], r[15][15], x[15], ans = 0;

long long p[15] = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37};

bool checkNumber(long long num) {
    for (long long i = 0; i < m - 1; i++) {
        if (num % (i + 2) != b[i]) {
            return false;
        }
    }
    return true;
}

int main() {
    cin >> m;
    for (long long i = 0; i < m - 1; i++) {
        cin >> b[i];
        for (long long j = n; j < 15; j++) {
            if (p[j] == i + 2) {
                a[n] = b[i];
                n++;
                break;
            }
        }
    }
    for (long long i = 0; i < n - 1; i++) {
        for (long long j = i + 1; j < n; j++) {
            r[i][j] = inv(p[i], p[j]);
        }
    }
    for (long long i = 0; i < n; ++i) {
        x[i] = a[i];
        for (long long j = 0; j < i; ++j) {
            x[i] = r[j][i] * (x[i] - x[j]);

            x[i] = x[i] % p[i];
            if (x[i] < 0) x[i] += p[i];
        }
    }
    long long multipl = 1;
    for (long long i = 0; i < n; i++) {
        ans += x[i] * multipl;
        multipl *= p[i];
    }
    while (!checkNumber(ans)) {
        ans += multipl;
    }
    cout << ans;
    return 0;
}