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#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef double db;
typedef pair<int, int> pii;
#define all(x) (x).begin(), (x).end()
#define sz(x) (x).size()
#define rep(i, l, r) for(int i=l; i<(r); i++)

ll nxt(){
    ll x;
    cin >> x;
    return x;
}

mt19937 rng(random_device{}());
int rd(int l, int r) {
	return uniform_int_distribution<int>(l, r)(rng);
}

void solve(){
    int n;
    cin >> n;
    vector<int> v(n);
    for(int i=0; i<n; i++) {
        cin >> v[i];
    }
    int l = 0;
    int r = n-1;
    while(v[l] == 0) l++;
    while(v[r] == 0) r--;

    n = r-l+1;

    int prev = 0;
    vector<int> tab;
    for(int i=0; i<n; i++) {
        int a = v[l+i];
        tab.push_back(a-prev);
        prev = a;
    }
    tab.push_back(-prev);
    for(int i=n; i>=2; i--) {
        bool ok = 1;
        if(i > 100){
            int randT = 5;
            while(randT--) {
                int j = rd(0, i-1);
                ll suma = 0;
                for(int k=j; k<=n; k+=i) {
                    suma+=tab[k];
                    if(suma < 0){
                        ok = 0;
                        break;
                    }
                }
                if(suma != 0) ok = 0;
                if(ok == 0) break;
            }
        }
        for(int j=0; j<i && ok; j++) {
            ll suma = 0;
            for(int k=j; k<=n; k+=i) {
                suma+=tab[k];
                if(suma < 0){
                    ok = 0;
                    break;
                }
            }
            if(suma != 0) ok = 0;
        }
        if(ok) {
            cout << i << "\n";
            return;
        }
    }
    cout << 1 << "\n";
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    // cin >> t;
    while(t--){
        solve();
    }
}