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
50
51
52
53
54
55
56
#include <iostream>
#include <vector>

using namespace std;

int count_distinct(vector<int> const& as) {
	int count = 0;
	vector<bool> used(as.size(), false);

	for(auto e : as) {
		if(!used[e]) {
			used[e] = true;
			count++;
		}
	}

	return count;
}

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

	int n, k;
	int ni = 1;
	uint64_t result = 0;
	vector<int> as{};
	vector<bool> used{};

	cin >> n >> k;
	as.resize(n);
	used.resize(n, false);

	for(auto& e : as) {
		cin >> e;
		e--;
	}

	if(count_distinct(as) < k) {
		cout << -1;
		return 0;
	}

	used[as[0]] = true;
	for(int i = 1; ni < k; i++) {
		if(!used[as[i]]) {
			used[as[i]] = true;
			result += i - ni;
			ni++;
		}
	}

	cout << result;

	return 0;
}