#include <bits/stdc++.h>
using namespace std;
#define int long long
int maxn = LLONG_MIN;
int minn = LLONG_MAX;
int a[100100];

signed main() {
	//freopen("room.in", "r", stdin);
	//freopen("room.out", "w", stdout);
	int n, x;
	cin >> n >> x;
	for(int i = 1;i <= n;i ++) {
		cin >> a[i];
	}
	int sum = x + 1;
	for(int i = 2;i <= n;i ++) {
		sum += min(a[i] - a[i - 1], x + 1);
	}
	cout << sum << "\n";
	return 0;
}