#pragma comment(linker, "/STACK:65777216")
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <queue>
#include <string>
#include <memory.h>
#include <iterator>
#define y1 trololoy1
#define y0 trololoy0
#define mem(A,X) memset(A,X,sizeof(A))
#define memo(A) memset(A,0,sizeof(A))
#define forn(I,B) for (int I=1;I<=(B);I++)
#define forg(H,V) for (int H=first[V];h;h=next[H])
#define rep(I,B) for (int I=0;I<(B);I++)
#define labs(X) (((X)>0)?(X):(-(X)))
#define ropen(X) freopen(X,"r",stdin)
#define wopen(X) freopen(X,"w",stdout)
#define rwopen(X) freopen(X".in","r",stdin);freopen(X".out","w",stdout)
#define pb push_back
#define mp make_pair
#define all(X) (X).begin(),(X).end()
#define sqr(X) ((X)*(X))

using namespace std;

typedef pair <int,int> pii;
typedef double ld;
typedef long long ll;
typedef pair <ll,ll> pll;
typedef vector<int> vi;
const int N=111111;
const int INF=111111111;
const double eps=1e-9;
const double pi=3.14159265358979;

int n,m,a[N],c[1001];
pii t[N];

inline bool check(int k){
    int l=1,r=k+1;
    memo(c);
    int kv=0,ans=0;
    forn(i,k+1) ++c[a[i]];
    while (r<=n){
        if (a[l]!=a[r] && c[a[l]]==1 && c[a[r]]==1) t[++kv]=pii(min(a[l],a[r]),max(a[l],a[r]));
        --c[a[l]];
        ++c[a[r+1]];
        ++l;++r;
    }
    sort(t+1,t+kv+1);
    forn(i,kv) if (t[i]!=t[i-1]) ++ans;
    return ans<=m;
}

int main(){
    scanf("%d%d",&n,&m);
    forn(i,n) scanf("%d",&a[i]);
    int l=1,r=n-2;
    while (l<r){
        int m=(l+r)/2;
        if (check(m)) r=m;
        else l=m+1;
    }
    if (r!=1 && check(r-1)) printf("%d\n",r-1);
    else printf("%d\n",r);
    return 0;
}