#include <bits/stdc++.h>   using namespace std;   struct InputReader {     char buf[1048576];     int p;     inline InputReader() { p = 1048576; }     inline void Flush() {       p = 0;       fread(buf, 1, 1048576, stdin);     }     inline char C() {       if (p >= 1048576) Flush();       return buf[p++];     }     inline char Readnum() {       char ch = C();       while (!isdigit(ch) && ch !=  - ) ch = C();       return ch;     }     inline void Readalpha(char &c) {       c = C();       while (!isalpha(c)) c = C();     }     int operator()() {       int ans = 0, fu = 1;       char ch = Readnum();       if (ch ==  - ) fu = -1, ch = C();       while (ch >=  0  && ch <=  9 ) {         ans = ans * 10 + ch -  0 ;         ch = C();       }       return ans * fu;     }     long long Readll() {       long long ans = 0LL, fu = 1LL;       char ch = Readnum();       if (ch ==  - ) fu = -1LL, ch = C();       while (ch >=  0  && ch <=  9 ) {         ans = ans * 10LL + ch -  0 ;         ch = C();       }       return ans * fu;     }     inline void Readstring(string &x) {       x.clear();       char ch = C();       while (!isdigit(ch) && !isalpha(ch) && ch !=  #  && ch !=  . ) ch = C();       while (isdigit(ch) || isalpha(ch) || ch ==  #  || ch ==  . ) {         x += ch;         ch = C();       }     }     inline void Readchstring(char s[]) {       int len = 0;       char ch = C();       while (!isdigit(ch) && !isalpha(ch)) ch = C();       while (isdigit(ch) || isalpha(ch)) {         s[len++] = ch;         ch = C();       }       s[len] =   0 ;     }     inline void Specialread(char &c) {       c = C();       while (!isdigit(c) && !isalpha(c) && c !=  #  && c !=  .  && c !=  =  &&              c !=  B )         c = C();     }   } In;   inline void Read(int &x) { x = In(); }   inline void Read(int &x, int &y) {     x = In();     y = In();   }   inline void Read(int &x1, int &x2, int &x3) {     x1 = In();     x2 = In();     x3 = In();   }   inline void Read(int &x1, int &x2, int &x3, int &x4) {     x1 = In();     x2 = In();     x3 = In();     x4 = In();   }   inline void Read(long long &x) { x = In.Readll(); }   inline void Read(long long &x, long long &y) {     x = In.Readll();     y = In.Readll();   }   inline void Read(long long &x1, long long &x2, long long &x3) {     x1 = In.Readll();     x2 = In.Readll();     x3 = In.Readll();   }   inline void Read(long long &x1, long long &x2, long long &x3, long long &x4) {     x1 = In.Readll();     x2 = In.Readll();     x3 = In.Readll();     x4 = In.Readll();   }   template <typename T>   void Read(T a[], int st, int ed) {     for (int(i) = (st); (i) <= (ed); ++(i)) Read(a[i]);   }   inline void FILEIO() {}   inline void FILEIO(string pname) {     freopen((pname +  .in ).c_str(),  r , stdin);     freopen((pname +  .out ).c_str(),  w , stdout);   }   inline void FILEIO_OICONTEST(string pname) {     freopen((pname +  .in ).c_str(),  r , stdin);     freopen((pname +  .out ).c_str(),  w , stdout);   }   void Printtime() {}   void END() {     Printtime();     exit(0);   }   template <typename T>   void END(T mes) {     cout << mes << endl;     END();   }   template <typename T>   void Print(T a[], int s, int t, char sp =    , char ed =   n ) {     if (s > t) return;     for (int i = s; i < t; i++) cout << a[i] << sp;     cout << a[t] << ed;     cout.flush();   }   template <typename T>   void Print(T a, int s = 0, int t = -1, char sp =    , char ed =   n ) {     if (t == -1) t = a.size() - 1;     for (int i = s; i <= t; i++) cout << a[i] << sp;     cout << ed;     cout.flush();   }   vector<int> Range(int l, int r) {     vector<int> ret{};     for (int(i) = (l); (i) <= (r); ++(i)) ret.push_back(i);     return ret;   }   const long long MOD = 998244353;   template <typename T>   T Mymo(const T &x) {     return x >= MOD ? x - MOD : x;   }   template <typename T>   void Mymod(T &x) {     x = x >= MOD ? x - MOD : x;   }   inline long long Pow(long long a, long long b, const long long p = MOD) {     long long ret = 1;     for (; b; a = a * a % p, b >>= 1LL)       if (b & 1LL) ret = ret * a % p;     return ret;   }   inline long long Inv(long long a, const long long p = MOD) {     return Pow(a, p - 2LL, p);   }   const int MAXN = 1024;   int n, k;   int a[MAXN], mxa;   long long ansl[131072];   int dpsum[MAXN][MAXN];   int Solve(int delta) {     if (delta > mxa / (k - 1)) return 0;     for (int(i) = 1; (i) <= (n); ++(i)) memset(dpsum[i], 0, k + 1 << 2);     int pre = 0;     int ans = 0;     for (int(i) = 1; (i) <= (n); ++(i)) {       while (pre != i - 1 and a[i] - a[pre + 1] >= delta) ++pre;       for (int(j) = (2); (j) <= (((i) < (k) ? (i) : (k))); ++(j)) {         int u = j == 2 ? pre : dpsum[pre][j - 1];         dpsum[i][j] = Mymo(dpsum[i - 1][j] + u);         if (j == k) {           ans = Mymo(ans + u);           Mymod(ans);         }       }     }     return ans;   }   int main() {     FILEIO();     Read(n, k);     Read(a, 1, n);     sort(a + 1, a + 1 + n);     mxa = a[n];     for (int(i) = (0); (i) <= (mxa); ++(i)) {       ansl[i] = Solve(i);     }     long long ans = 0;     for (int(i) = (0); (i) <= (mxa); ++(i)) {       long long cnt = ansl[i] - ansl[i + 1] + MOD;       ans += cnt * i % MOD;       Mymod(ans);     }     cout << ans << endl;     END();   }