#include <fstream>
#include <vector>
#include <set>
#include <algorithm>

using namespace std;

ifstream fin("secv.in");
ofstream fout("secv.out");

vector<int>v;
int n;

int solve()
{
	vector<int> tmp = v;

	sort(tmp.begin(), tmp.end());
	set<int>s;
	for(auto x : tmp)
        s.insert(x);
    tmp.resize(s.size());
    copy(s.begin(),s.end(),tmp.begin());

	int sol = n + 1;
	for(int i = 0;i<n;++i)
	{
		int index = 0, j;
		for(j = i;j < n && index < (int)tmp.size();++j)
		{
			if(v[j] == tmp[index])
				++index;
		}
		if(index == (int)tmp.size())
			sol = min(sol, j - i);
	}
	if(sol == n + 1)
		return -1;
	return sol;
}

int main()
{
    int x;
    fin >> n;
    for(int i=1;i<=n;++i)
    {
        fin >> x;
        v.push_back(x);
    }

    fout << solve();
    return 0;
}