#include <fstream>
#include <cstring>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <algorithm>
#include <iomanip>
#include <cmath>
#include <cstdlib>
#include <ctime>

using namespace std;
ifstream cin("secv.in");
ofstream cout("secv.out");
using ll = long long;
//#define int ll
using pi = pair<int,int>;
using pll = pair<ll, ll>;

#define pb push_back
#define x first
#define y second

const int MOD = 1e9+7, INF = 1e9, NMAX = 2e5+1;
ll v[NMAX], dp[NMAX], last[NMAX];
map<int, int> f, norm;
void solve()
{
    ll n, i, cnt = 0;
    cin >> n;
    for(i = 1; i <= n; i++)
    {
        cin >> v[i];
        f[v[i]] = 1;
    }
    for(auto it: f)
        norm[it.first] = ++cnt;
    for(i = 1; i <= n; i++)
        v[i] = norm[v[i]];
    ll ans = INF;
    for(i = 1; i <= n; i++)
    {
        last[v[i]] = i;
        if(v[i] == 1)
            dp[i] = 1;
        else
        {
            if(last[v[i] - 1] && dp[last[v[i] - 1]])
                dp[i] = dp[last[v[i] - 1]] + i - last[v[i]-1];
        }
        if(v[i] == cnt && dp[i])
            ans = min(ans, dp[i]);
    }
    if(ans == INF)
        cout << -1;
    else
        cout << ans;

}
int main()
{
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    int T;
    T = 1;
    while(T--)
        solve();
    return 0;
}