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
#include<iostream>
#include<vector>
#include<algorithm>
#include<set>
using namespace std;

int present[500001] = {};

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n, k, e, cnt = 0;
    cin >> n >> k;

    vector<int> to_swap;
    for (int i = 0; i < n; i++) {
        cin >> e;
        if (i < k) {
            if (present[e] == 1) {
                to_swap.push_back(i);
            }
            present[e] = 1;
        }
        else {
            if (to_swap.empty()) {
                break;
            }
            if (present[e] == 0) {
                cnt += i - to_swap.back();
                to_swap.pop_back();
            }
            present[e] = 1;
        }
    }
    if (to_swap.empty()) {
        cout << cnt;
    }
    else {
        cout << -1;
    }

    return 0;
}