#include <iostream>
#include <set>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1e6 + 10, M = 2010;
int n, m;
int gun[N], num[M];

int main() {
    scanf("%d%d", &n, &m);
    for(int i = 0; i < n; i++) scanf("%d", &gun[i]);
    set<int> s;
    int res = N;
    for(int i = 0, j = 0; i < n; i++) {
        int t = gun[i];
        if(t == 0) continue;
        s.insert(t);
        num[t]++;
        if(s.size() == m) {
            for(; j < i; j++)
                if(--num[gun[j]] == 0) {
                    num[gun[j]]++;
                    break; 
                }
            res = min(res, i - j + 1);
        }
    }
    if(res == N) cout << -1 << endl;
    else cout << res << endl;
    return 0;
}