1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
#include <bits/stdc++.h>
#define pii pair<int, int>
#define For(i, l, r) for (int i=l;(l<=r?i<=r:i>=r);(l<=r?i++:i--))
#define DEBUG
#ifdef DEBUG
auto operator<<(auto &o,auto p)->decltype(p.first,o){return o<<'('<<p.first<<", "<<p.second<<')';}
auto operator<<(auto &o,auto x)->decltype(x.end(),o){o<<'{';int i=2;for(auto &e:x)o<<(", ")+i<<e,i=0;return o<<'}';}
#define LOG(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X);
#else
#define LOG(x...)(void)0
#endif
#define int long long
using namespace std;

const int M = 100005;
int n;
vector<int> a, c;

bool check(int k){
    int sum = 0;
    for (int i = 0; i < n; i++){
        if (i >= k)
            sum -= c[i - k];
        c[i] = a[i] - sum;
        if (c[i] < 0)
            return 0;
        if (i + k > n){
            if (c[i])
                return 0;
        }
        else
            sum += c[i];
    }
    return 1;
}

void solve(){
    cin >> n;
    a = vector<int>(n);
    c = vector<int>(n);
    int sum = 0;
    for (int i = 0; i < n; i++){
        cin >> a[i];
        sum += a[i];
    }
    int best = 1;
    vector<bool> ok(n + 1);
    vector<int> divs;
    for (int i = 2; i <= n; i++){
        if (i <= best)
            continue;
        if (sum % i == 0){
            bool o = 1;
            for (auto el: divs)
                if (i % el == 0 && !ok[el]){
                    o = 0;
                    break;
                }
            if (o && check(i)){
                best = max(best, i);
                ok[i] = 1;
            }
            divs.push_back(i);
        }
    }
    cout << best << '\n';
}

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