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
57
58
59
#include<bits/stdc++.h>

#define vi vector<int>
#define vvi vector<vi>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vii vector<pii>
#define vb vector<bool>
#define vvb vector<vb>
#define vl vector<ll>
#define endl '\n'
#define turbo ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define pb push_back
#define ll long long
#define f first
#define s second

using namespace std;

int n, k;
vi v;

set<int> se, ind;

int main()
{
    turbo
    cin >> n >> k;
    v = vi(n);
    for(auto &it : v)
        cin >> it;
    for(int i = 0; i < n; i++)
        if(se.find(v[i]) == se.end())
        {
            se.insert(v[i]);
            if(i >= k)
                ind.insert(i);
        }
    ll res = 0;
    for(int i = 0; i < k; i++)
    {
        if(se.find(v[i]) != se.end())
            se.erase(v[i]);
        else
        {
            if(ind.empty())
            {
                res = -1;
                break;
            }
            else
            {
                res += ((*ind.begin())-i);
                ind.erase(ind.begin());
            }
        }
    }
    cout << res << endl;
}