#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
#define maxn 5010

int N, nre, sol;
int A[maxn], E[maxn];

void unique() {
    sort(E+1, E+N+1);
    E[0] = -1;

    for(int i=1; i<=N; i++) {
         if(E[i] != E[i-1]) {
              nre++;
              E[nre] = E[i];
         }
    }
}

int verif(int pos) {
    int start = pos, lst = 1;
    while(pos <= N) {
         if(A[pos] == E[lst]) {
              lst++;
         }
         if(lst > nre) return pos-start+1;
         pos++;
    }
    return maxn;
}

int main() {
    FILE *f1=fopen("secv.in", "r"), *f2=fopen("secv.out", "w");
    int i, j;

    fscanf(f1, "%d\n", &N);
    for(i=1; i<=N; i++) {
         fscanf(f1, "%d", &A[i]);
         E[i] = A[i];
    }

    unique();

    sol = maxn;
    for(i=1; i<=N; i++) {
         //incep un nou subsir pe pozitia i
         sol = min(sol, verif(i));
    }

    if(sol == maxn) sol = -1;
    fprintf(f2, "%d\n", sol);
    fclose(f1); fclose(f2);
    return 0;
}