#include <fstream>
#include <algorithm>

using namespace std;

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

int v[5005],w[5005],n,i,j,k,x,secv,minim,ok,okf;

int main () {

    fin>>n;

    for (i=1;i<=n;i++) {
        fin>>v[i];
        w[i]=v[i];
    }
    sort (w+1,w+n+1);
    k=1;
    for (i=2;i<=n;i++)
        if (w[i]!=w[k])
            w[++k]=w[i];


    minim=n;
    v[0]=-1;
    for (i=n;i>=k-1;i--) {

        if (v[i]==w[k]) {
            ok=1;
            for (j=i,x=k;j>=1;j--){
                if (v[j]==w[x]){
                    x--;
                    if (x==0){
                        ok=0;
                        break;
                    }
                }
            }if (ok==0) {
                okf=1;
                secv=i-j+1;
                if (secv<minim)
                    minim=secv;
            }
        }
    }

    if (okf==1)
        fout<<minim<<"\n";
    else
        fout<<"-1\n";

    return 0;
}