56
 1
 46
 63478
 7578
 56056
 78
 66873
 8149
 35708
 81207
 41385
 37317
 74424
 67817
 684
 15
 96992
 38798
 19715
 627
 39509
 45899
 31893
 1515
 33
 95298
 27443
 60879
 99
 34378
 57113
 36655
 63359
 873
 67341
 100000
 42863
 35
 250
 573
 23
 871
 15748
 92763
 9564
 42602
 38
 42237
 70878
 93764
 303

-1
 -1
 4
 -1
 3
 -1
 4
 2
 2
 -1
 6
 15
 -1
 21
 73
 -1
 2
 -1
 76
 -1
 2
 -1
 -1
 3
 2
 2
 4
 2
 2
 2
 -1
 2
 -1
 34
 18
 2
 -1
 -1
 -1
 5
 3
 -1
 -1
 8
 22
 3
 17
 -1
 18
 -1
 -1
 2

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

#define dist2D(x1, y1, x2, y2)            ((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2))
#define dist3D(x1, y1, z1, x2, y2, z2)    ((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2) + (z1 - z2) * (z1 - z2))
#define EPS                         1e-16
#define endl                        "\n"
#define FastIO                      ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define FI                          freopen("in.txt", "r", stdin)
#define FO                          freopen("out.txt", "w", stdout)
#define fap(x)                      cout << "WTH: " << x << endl
#define ff                          first
#define INF              1000000000000000000
#define ld                          long double
#define ll                          long long
#define mem(x,y)                    memset(x, y, sizeof x)
#define mp                          make_pair
#define msi                         map<string, int>
#define mii                         map<int, int>
#define mis                         map<int, string>
#define MOD                         1000000007
#define PI                          acos(-1.0)
#define PQ                          priority_queue
#define pb                          push_back
#define pib                         pair<int, bool>
#define pii                         pair<int, int>
#define pll                         pair<ll, ll>
#define sfi(x)                      scanf("%d", &x)
#define sfii(x,y)                   scanf("%d %d", &x, &y)
#define sfiii(x,y,z)                scanf("%d %d %d", &x, &y, &z)
#define siz(x)                      (int)x.size()
#define sortv(v)                    sort(v.begin(), v.end())
#define ss                          second
#define timeTaken                   endd = clock(); cout << (double) (endd - beginn) / CLOCKS_PER_SEC * 1000 << endl
#define timeInit                    clock_t beginn = clock(), endd
#define ull                         unsigned long long
#define umsi                        unordered_map<string, int>
#define umii                        unordered_map<int, int>
#define umis                        unordered_map<int, string>
#define vb                          vector<bool>
#define vi                          vector<int>
#define vvi                         vector<vi>
#define vii                         vector<pii>
#define vvii                        vector<vii>
#define vll                         vector<ll>
#define vvll                        vector<vll>
#define vpll                        vector<pll>

/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <functional>
using namespace __gnu_pbds;
typedef tree<int,null_type, less<int>, rb_tree_tag,
        tree_order_statistics_node_update> ordered_set;

//os.order_of_key(v): returns how many elements strictly less than v
//os.find_by_order(k - 1): returns kth smallest element's iterator
*/

template<class T> class compare {
public:
    bool operator() (pair<T, T> &x, pair<T, T> &y) {
        if (x.first == y.first) {
            return x.ss > y.ss;
        }
        return x.ff > y.ff;
    }
};

//template<class T> ostream& operator<<(ostream &os,const pair<T,T> &a) { os<<a.ff<<" "<<a.ss; }
ll power(ll a, int b) {
    ll po = 1;
    while (b) {
        if (b & 1)
            po *= a;
        a *= a;
        b >>= 1;
    }
    return po;
}

template<class T> pair<T, T> operator + (const pair<T, T> &a, const pair<T, T> &b) { return {a.ff + b.ff, a.ss + b.ss}; }
template<class T> pair<T, T> operator - (const pair<T, T> &a, const pair<T, T> &b) { return {a.ff - b.ff, a.ss - b.ss}; }
template<class T> pair<T, T> operator * (const pair<T, T> &a, const pair<T, T> &b) { return {a.ff * b.ff, a.ss * b.ss}; }
template<class T> pair<T, T> operator % (const pair<T, T> &a, const pair<T, T> &b) { return {a.ff % b.ff, a.ss % b.ss}; }
template<class T, class U> pair<T, T> operator + (const pair<T, T> &a, const U &b) { return {a.ff + b, a.ss + b}; }
template<class T, class U> pair<T, T> operator * (const pair<T, T> &a, const U &b) { return {a.ff * b, a.ss * b}; }

int Set(int N, int pos) { return N = N | (1 << pos); }
int reset(int N, int pos){ return N = N & ~ (1 << pos); }
bool check(ll N, int pos){ return (bool) (N & (1LL << pos)); }

///=======================================template=======================================///

const int maxn = 100005;
bitset<20> mex[maxn];
vi grandy, win, prexor;

int main() {
    //FI;//FO;
    FastIO;//timeInit;

    int n;
    cin >> n;
    win.assign(n + 1, INT_MAX);
    grandy.assign(n + 1, 0);
    prexor.assign(n + 1, 0);

    for (int i = 0; i <= n; i++) {
        mex[i].set();
    }

    for (int i = 2; i <= n; i++) {

        grandy[i] = mex[i]._Find_first();
        prexor[i] = grandy[i] ^ prexor[i - 1];
        int sum = i;
        for (int j = i - 1; j > 0; j--) {
            sum += j;
            if (sum > n)
                break;
            mex[sum] = mex[sum].reset(prexor[i] ^ prexor[j - 1]);
            if (prexor[i] ^ prexor[j - 1] == 0) {
                win[sum] = min(win[sum], i - j + 1);
            }
        }
    }

    if (grandy[n] != 0)
        cout << win[n] << endl;
    else cout << -1 << endl;

    //timeTaken;
    return 0;
}