1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
#include <bits/stdc++.h>
#define ll long long
#define newl cout << "\n"
#define fastio ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
using namespace std;
const int iinf = (int) 1e9 + 111;
const long long inf = (long long) 1e18 + iinf;
const int N = 1e6 + 111;
#define list sdkfndsf


int32_t main(){
    int n, k;
    cin >> n >> k;
    vector<int> v(n);
    vector<int> mp(n + 1, 0);
    vector<int> mp1(n + 1, 0);
    for(int &it : v){
        cin >> it;
    }
    for(int i = 0; i < k; i++){
        mp[v[i]]++;
    }
    for(int i = k; i < n; i++){
        mp1[v[i]]++;
    }
    queue<int> list;
    for(int i = k; i < n; i++){
        if (mp1[v[i]] != -1 && !mp[v[i]]){
            list.emplace(i);
            mp1[v[i]] = -1;
        }
    }
    int ans = 0;
    for(int i = k - 1; i >= 0; i--){
        if (mp[v[i]] == 1)
            continue;
        if (list.empty()){
            ans = -1;
            break;
        }
        int ind = list.front();
        list.pop();
        ans+= ind - i;
        mp[v[i]]--;
    }
    cout << ans;
    return 0;
}