#include <algorithm>
#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

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

int n, v[5005], ap[5005], res = 5005;
int norm[5005];

void normalizare() {
	for (int i = 1; i <= n; ++i)
		norm[i] = v[i];
	
	sort(norm + 1, norm + n + 1);
	for (int i = 1; i <= n; ) {
		int j = i;
		while (norm[i] == norm[j] and j <= n)
			++j;
		norm[++norm[0]] = norm[i];
		i = j;
	}
	
	for (int i = 1; i <= n; ++i) {
		int p = 0;
		for (int cnt = 1 << 12; cnt; cnt >>= 1)
			if (p + cnt <= norm[0] and norm[p + cnt] <= v[i])
				p += cnt;
		v[i] = p;
	}
}

int lap[5005];

int main() {
	fin >> n;
	for (int i = 1; i <= n; ++i)
		fin >> v[i];
	
	if (n == 0 || n == 1) {
		fout << n << '\n';
		return 0;
	}
	normalizare();
	
	for (int i = 1; i <= n; ++i) {
		if (v[i] == 1)
			lap[1] = i;
		else
			lap[v[i]] = lap[v[i] - 1];
		if (v[i] == norm[0])
			res = min(res, i - lap[v[i]] + 1);
	}
	
	if (res > n)
		fout << "-1\n";
	else
		fout << res << '\n';

	fin.close();
	fout.close();
}