// 顶针势力正在不断地扩大。
#include <bits/stdc++.h>
using i64 = long long;

const int maxn = 1e5 + 5;
i64 d[maxn],k;
int n;

int main() {
	freopen("kanmoo.in","r",stdin);
	freopen("kanmoo.out","w",stdout);
	scanf("%d %lld",&n,&k);
	i64 ans = 0;
	for(int i = 1;i <= n;++ i) {
		scanf("%lld",&d[i]);
		if(i == 1)
			ans = k + 1;
		else {
			if(d[i] - d[i - 1] > k)
				ans += k + 1;
			else
				ans += d[i] - d[i - 1];
		}
	}
	printf("%lld\n",ans);
	return 0;
}