#include <bits/stdc++.h>
#define int long long
#define double long double
#define Task "E"
#define READFILE freopen(Task".inp", "r", stdin)
#define WRITEFILE freopen(Task".out", "w", stdout)
#define double long double
#define oo 1e18
#define FAST ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define mp make_pair
#define pb push_back
#define X first
#define Y second
#define watch(x) cout << (#x) << " = " << x << endl
#define debug(x) cout << (#x) << " = " << x << endl
#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define endl '\n'
#define max3(a,b,c) max(max(a, b), c)
#define max4(a,b,c,d) max(max(a, b), max(c, d))
#define min4(a,b,c,d) min(min(a, b), min(c, d))
#define debug4(a,b,c,d) watch(a);watch(b);watch(c);watch(d)
#define ever (;true;)
#define maxn 505

#define PI 3.14159265

using namespace std;

typedef pair < int, int > ii;
typedef pair < int, ii > iii;
typedef pair < ii, ii > iiii;
typedef vector < int > vi;
typedef vector < ii > vii;
typedef vector < vi > vvi;
typedef vector < iii > viii;
typedef vector < vii > vvii;
typedef vector < iiii > viiii;
typedef vector < vvi > vvvi;

const int N = 1e5 + 5;

struct HashSet{
    int base1, mod1, base2, mod2;

    int Power1[N], Power2[N];

    HashSet(int b1 = 1, int m1 = 1, int b2 = 1, int m2 = 1){
        base1 = b1;
        mod1 = m1;
        base2 = b2;
        mod2 = m2;
        Power1[0] = Power2[0] = 1;
        for (int i = 1; i <= 100000; ++i){
            Power1[i] = Power1[i-1]*base1%mod1;
            Power2[i] = Power2[i-1]*base2%mod2;
        }
    }

    ii GetHash(int arr[], int arrsize = 0){
        ii Hash = ii(0, 0);
        for (int i = 0; i < arrsize; ++i){
            Hash.X += Power1[arr[i]];
            if (Hash.X >= mod1) Hash.X %= mod1;
            Hash.Y += Power2[arr[i]];
            if (Hash.Y >= mod2) Hash.Y %= mod2;
        }
        return Hash;
    }


}HS(115079, 1000004249, 763787, 1000004459);

int n;
int a[N];

viii res;

void init(){
    FAST;
    if (fopen(Task".inp", "r")){
        READFILE;
        WRITEFILE;
    }
    cin >> n;
    for (int i = 1; i <= n; ++i) cin >> a[i];
}

map < ii, int > Map;

void Process(int len){
    if (len < 1 || len >= n) return;
    if (n % len) return;
    Map.clear();
    for (int i = 1; i <= n; i += len){
        ii cur = HS.GetHash(a + i, len);
        Map[cur]++;
    }
    if (Map.size() == 2){
        vi p;
        for (auto T : Map) p.pb(T.Y);
        sort(all(p), greater < int > ());
        res.pb(iii(len, ii(p[0], p[1])));
    }
}

signed main(){
    init();
    for (int i = 1; i * i <= n; ++i){
        if (n % i == 0){
            Process(i);
            if (i * i != n) Process(n / i);
        }
    }
    sort(all(res));
    cout << ((int)res.size() == 0 ? -1 : (int)res.size()) << endl;
    for (iii T : res) cout << T.X << ' ' << T.Y.X << ' ' << T.Y.Y << endl;
    return 0;
}