#include <iostream>
#include <cstdio>
#include <map>
#define MAXN 5050
#define inf 0x3fffffff

using namespace std;

int n;
int a[MAXN];
map<int, int> nr;
map<int, int> ult;

void citire()
{
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
		scanf("%d", &a[i]);
		nr[a[i]] = 1;
    }
}

void solve()
{
	int best = inf;
    for (int i = 1; i <= n; i++) {
		if (a[i] == nr.begin()->first)
			ult[a[i]] = i;
		else {
			auto it = nr.find(a[i]);
			it--;
			int look = it->first;
            auto it2 = ult.find(look);
            if (it2 != ult.end()) {
                ult[a[i]] = it2->second;
				it++; it++;
				if (it == nr.end()) {
					int crt = i - (it2->second) + 1;
					if (crt < best)
						best = crt;
				}
            }
		}
    }
    if (best == inf)
		best = -1;
    printf("%d", best);
}

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

    citire();
    solve();


    return 0;
}