#include <cstdio>

using namespace std;
int v[15005];
int f[1005];
int verif[1005];
int main()
{
    freopen("secv.in","r",stdin);
    freopen("secv.out","w",stdout);
    int n,p,i,x,lmin=20000,st=0,dr=0,cnt=0;
    scanf("%d%d",&n,&p);
    for(i=1;i<=n;++i)
    {
        scanf("%d",&v[i]);
        verif[v[i]]=1;
    }
    for(st=dr=1; dr<=n; ++dr)
        {
            f[v[dr]]++;
                if(f[v[dr]]==1&&verif[v[dr]]==1)
                    cnt++;
            while(st<=dr&&cnt==p)
            {
                if(dr-st<lmin)
                    lmin=dr-st;

                if(verif[v[st]]==1)
                {
                    f[v[st]]--;
                    if(f[v[st]]==0)
                    {
                        cnt--;

                    }
                }
                st++;
            }
        }
        if(lmin==20000)
        {printf("-1");return 0;}
        printf("%d\n",lmin);

    return 0;
}