#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

const long long INF = LLONG_MAX / 2;

int main()
{
    int n, p;
    cin >> n >> p;
    vector<int> h(n);
    for(int i=0; i<n; ++i)
        cin >> h[i];

    vector<vector<long long> > dp(n, vector<long long>(2, INF));
    dp[0][0] = 0;
    for(int i=0; i<n-1; ++i){
        for(int j=0; j<2; ++j){
            for(int k=0; k<2; ++k){
                dp[i+1][k] = min(dp[i+1][k], dp[i][j] + p);
            }
        }
        dp[i+1][0] = min(dp[i+1][0], dp[i][0] + max(0, h[i+1] - h[i]));
        dp[i+1][1] = min(dp[i+1][1], dp[i][1] + max(0, h[i] - h[i+1]));
    }

    long long ans = min(dp[n-1][0], dp[n-1][1]);
    cout << ans << endl;

    return 0;
}