#include <bits/stdc++.h> using namespace std; // Simple Define #define ALISA_MIKHAILOVNA_KUJOU \ ios_base::sync_with_stdio(0); \ cin.tie(0); \ cout.tie(0) #define ARYA_IS_THE_BEST freopen("input.inp", "r", stdin) #define SHE_IS_MY_WIFE freopen("output.out", "w", stdout) #define ll long long #define ull unsigned long long #define fi first #define se second #define vi vector<int> #define vstr vector<string> #define vc vector<char> #define vb vector<bool> #define vpii vector<pair<int, int>> #define pii pair<int, int> #define pill pair<int, long long> #define vpill vector<pair<int, long long>> #define vll vector<long long> #define all(a) a.begin(), a.end() #define rall(a) a.rbegin(), a.rend() #define fr(i, a, b) for (int i = (a); i <= (b); i++) #define fd(i, a, b) for (int i = (a); i >= (b); i--) #define el cout << "\n" #define elif else if // bitwise operator #define MASK(i) (1 << (i)) #define c_bit(i) __builtin_popcountll(i) #define BIT(x, i) ((x) & MASK(i)) #define SET_ON(x, i) ((x) | MASK(i)) #define SET_OFF(x, i) ((x) & ~MASK(i)) #define getbit(x, i) ((x >> i) & 1) void solve() { int n, k; cin>>n>>k; vll t(n,0); for (ll& x: t) cin>>x; int target=((t[n-1]+1)-t[0])/k; ll ans=0; int i, j; for (i=0;i<n-1; ){ j=i; while (j<n && (t[j]+1)-t[i]<=target) j++; j--; ans+=(t[j]+1-t[i]); i=j+1; } if (i<n) ans+=(t[i]+1)-t[i]; cout<<ans; } int main() { ALISA_MIKHAILOVNA_KUJOU; int t = 1; // cin >> t; while (t--) solve(); return 0; }