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#define FOR(i,a,b) for(int i=(int)(a); i<(int)(b); ++i)
#define ulli unsigned long long int
#include <vector>
#include <cstdio>
using namespace std;

int n;
vector<int> P;

vector<int> sub;
bool test_length(int L) {
    FOR(i,0,sub.size()) sub[i] = 0;
    int currently_open = 0;
    FOR(i,0,P.size()) {
        currently_open -= sub[i];
        if (currently_open < 0) return false;
        if (currently_open > P[i]) return false;
        int missing = P[i] - currently_open;
        currently_open += missing;
        if (missing>0) {
            if (i+L>=(int)sub.size()) return false;
            sub[i+L] += missing;
        }
    }
    if (currently_open!=0) return false;
    return true;
}

int main() {

    // Read input
    scanf("%d", &n);
    FOR(i,0,n) {
        int a; scanf("%d", &a);
        if (a==0 && P.empty()) continue;
        if (i>0 && a==0 && P.back()==0) continue;
        P.push_back(a);
    }
    while (!P.empty() && P.back()==0) P.pop_back();
    P.push_back(0);
    sub.resize(P.size());

    // Calculate
    int result = 1;
    vector<bool> lengths(P.size()+1, true);
    lengths[0] = false;
    FOR(L,2,lengths.size()) {
        if (!lengths[L]) continue;
        lengths[L] = test_length(L);
        if (!lengths[L]) {
            for(int iL=L; iL<(int)lengths.size(); iL+=L) lengths[iL] = false;
        } else {
            result = L;
        }
    }

    printf("%d\n", result);
    return 0;
}