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
#include<bits/stdc++.h>

#define st first
#define nd second
#define pb(x) push_back(x)
#define pp(x) pop_back(x)
#define mp(a, b) make_pair(a, b)
#define all(x) (x).begin(), (x).end()
#define rev(x) reverse(all(x))
#define sor(x) sort(all(x))
#define sz(x) (int)(x).size()
#define rsz(x) resize(x)

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii > vii;
typedef vector<ll> vl;
typedef vector<pll> vll;
typedef string str;
#define BOOST ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
const int mx_N = 5*1e5+10;
bool B[mx_N];
int main()
{
    BOOST
    ll n, k;
    cin>>n>>k;
    int a;
    ll ans = 0;
    int dif = 0;
    for(int i = 0  ; i < n;  i++)
    {
        cin>>a;
        if(!B[a])
        {
            B[a] = true;
            ans+=(i-dif);
            dif++;
            if(dif == k)
            {
                cout<<ans;
                return 0;
            }
        }
    }
    cout<<-1;
    return 0;
}