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

using namespace std;

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

int n, ans, v[5005];
vector<int> a;

int main() {
    fin >> n;
    ans = n + 1;
    for(int i = 1; i <= n; i++) {
        fin >> v[i];
        a.push_back(v[i]);
    }
    sort(a.begin(), a.end());
    a.erase(unique(a.begin(), a.end()), a.end());
    for(int i = 1; i <= n; i++) {
        int ind = 0;
        for(int j = i; j <= n; j++) {
            if(v[j] == a[ind]) {
                ind++;
            }
            if(ind == a.size()) {
                ans = min(ans, j - i + 1);
                break;
            }
        }
    }
    fout << (ans == n + 1 ? -1 : ans) << "\n";
    return 0;
}