#include <iostream>
#include <queue>
#include <vector>
#include <algorithm>
using namespace std;
const int maxn = 1e5 + 10;
const int INF = 2e9;
vector<pair<int, int>> graph[maxn];
struct node {
    int idx, shortest_path;
    node() {}
    node(int _idx, int _shortest_path) {
        idx = _idx;
        shortest_path = _shortest_path;
    }
    bool operator < (const node & tmp) const {
        return shortest_path > tmp.shortest_path;
    }
};
int main(){
    int n, v;
    cin >> n >> v;
    
    vector<int> portal(n);
    for(int i = 0; i < n; i++) {
        cin >> portal[i];
    }
    
    vector<bool> visited(n, false);
    vector<bool> portal_visited(n, false);
    vector<int> dist(n, INF);
    priority_queue<node> pq;
    pq.push(node(0, 0));
    dist[0] = 0;
    
    while(!pq.empty()) {
        node c = pq.top();
        pq.pop();
        
        if(c.idx == n - 1) {
            cout << c.shortest_path << endl;
            break;
        }
        if(visited[c.idx]) continue;
        visited[c.idx] = true;
        if(c.idx + 1 < n) {
            pq.push(node(c.idx + 1, c.shortest_path + 1));
        }
        if(c.idx - 1 >= 0) {
            pq.push(node(c.idx - 1, c.shortest_path + 1));
        }
        
        if(!portal_visited[portal[c.idx]]) {
            for(int i = 0; i < n; i++) {
                if(portal[i] == portal[c.idx]) {
                    pq.push(node(i, c.shortest_path + v));
                }
            }
            portal_visited[portal[c.idx]] = true;
        }
    }
    
    
    return 0;
}