#define DEBUG 0
#include <bits/stdc++.h>
using namespace std;
#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}
// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
public:
template<typename T>
_Debug& operator,(T val) {
cout << val << endl;
return *this;
}
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif
// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back
// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;
// ---------- END OF TEMPLATE ----------
int X[100000];
LLI l[1000][1000],r[1000][1000];
int main() {
int i;
int N,K,T;
scanf("%d %d %d",&N,&K,&T),K--;
for (i = 0; i < N; i++) scanf("%d",&X[i]);
int j;
int s = 0,e = 1e9;
while (s < e) {
int m = (s+e) / 2;
for (i = K; i >= 0; i--) {
for (j = K; j < N; j++) {
if ((i == K) && (j == K)) l[K][K] = r[K][K] = X[K];
else {
l[i][j] = 1e18,r[i][j] = -1e18;
int t = j-i;
if (i < K) {
LLI L = max(X[i]-(LLI) t*m,l[i+1][j]-m);
LLI R = min(X[i]+(LLI) t*m,r[i+1][j]+m);
if (L <= R) l[i][j] = min(l[i][j],L),r[i][j] = max(r[i][j],R);
}
if (j > K) {
LLI L = max(X[j]-(LLI) t*m,l[i][j-1]-m);
LLI R = min(X[j]+(LLI) t*m,r[i][j-1]+m);
if (L <= R) l[i][j] = min(l[i][j],L),r[i][j] = max(r[i][j],R);
}
}
}
}
if (l[0][N-1] <= r[0][N-1]) e = m;
else s = m+1;
}
printf("%d\n",(s+T-1)/T);
return 0;
}
