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
#include <bits/stdc++.h>

int main() {
    std::ios_base::sync_with_stdio(0); std::cin.tie(NULL);
    int n, k;
    std::cin >> n >> k;

    std::vector<int> v(n, 0);
    for (int i = 0; i < n; i++) std::cin >> v[i];

    std::vector<int> found(n+1, 0);

    int res = 0;
    int found_cnt = 0;

    for (int i = 0; i < n && found_cnt < k; i++) {
        if (!found[v[i]]) {
            found[v[i]] = 1;
            res += i - found_cnt;
            found_cnt++;
        }
    }
    if (found_cnt < k) {
        std::cout << "-1\n";
    } else 
        std::cout << res << "\n";
}