#include <bitset>
#include <cmath>
#include <algorithm>
#include <numeric>
#include <deque>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <unordered_map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#define NMAX 5001
#define MAX 150001
#define pb push_back
#define MOD 1000000007
#define nl '\n'
#define INF 0x3f3f3f3f3f3f3
#define pii1 pair<int, pair<int,int>>  (1,(1,2));
#define int long long
#define pii pair<int,int>
#define tpl tuple<int,int,int>
using namespace std;
ifstream fin("secv.in");
ofstream fout("secv.out");
int n,v[NMAX],cnt,ans=INF;
unordered_map<int,int>f;
vector<pii>dp(NMAX);

signed main()
{
    fin>>n;
    for(int i=1;i<=n;++i) {
        fin >> v[i];
        if(!f[v[i]])
        {
            cnt++;
            f[v[i]]=1;
        }
    }


    for(int i=1;i<=n;++i)
    {
        dp[i]={1,0};
        for(int j=1;j<i;++j)
        {
            if(v[j]<v[i])
            {
                if(dp[j].first+1>=dp[i].first)
                {
                    dp[i].first=dp[j].first+1;
                    dp[i].second=j;
                }
            }
        }
    }
    for(int i=1;i<=n;++i)
    {
//        auto[x,y]=dp[i];
//        cout<<x<<" "<<y<<nl;
        int pos=i;
        while(dp[pos].second!=0)
        {
            pos=dp[pos].second;
        }
        if(dp[i].first==cnt)
        {
            ans=min(ans,(i-pos+1));
        }
    }
    if(ans==INF)
    {
        fout<<-1;
        return 0;
    }
    fout<<ans;







    return 0;
}