#include<cstdio>
#include<fstream>
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<bitset>
#include<deque>
#include<queue>
#include<set>
#include<map>
#include<cmath>
#include<cstring>
#include<ctime>
#include<cstdlib>
#include<unordered_map>

#define ll long long
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define pll pair<ll,ll>

using namespace std;

const int nmax = 5005;
const int inf = 1 << 30;

int n, i, j, p, sol, m, a[nmax], v[nmax];

set<int> s;

int main()
{
    freopen("secv.in", "r", stdin);
    freopen("secv.out", "w", stdout);

    scanf("%d", &n);

    if(n <= 1)
    {
        printf("%d\n", n);
        return 0;
    }

    for(i = 1; i <= n; i++)
    {
        scanf("%d", &a[i]);
        s.insert(a[i]);
    }

    for(auto it : s)
        v[++m] = it;

    sol = inf;

    for(i = 1; i <= n; i++)
        if(a[i] == v[1])
        {
            p = 2;
            for(j = i + 1; j <= n; j++)
            {
                if(a[j] == v[p]) p++;
                if(p > m) break;
            }
            if(j <= n) sol = min(sol, j - i + 1);
        }

    sol = sol == inf ? -1 : sol;

    printf("%d\n", sol);

    return 0;
}