#include <bits/stdc++.h>
using namespace std;
int N,K;
long long int T;
int lst[1100];
int main(){
scanf(" %d",&N);
scanf(" %d",&K);
scanf(" %lld",&T);
for(int i = 1; i <= N; i++) scanf(" %d",&lst[i]);
int s = 0;
int e = 1e9;
while(s != e){
int m = (s + e)/2;
m *= 2;
long long int cesh = T * m;
int it = K - 1;
int it1 = K + 1;
pair<long long int, long long int> profeet = {0,0};
pair<long long int, long long int> profeet1 = {0,0};
bool one = false;
while(it != 0 && (!one || profeet.first < 0) ){
one = true;
profeet.first += T * m - (lst[it + 1] - lst[it]);
profeet.second = min(profeet.second,profeet.first - T * m);
it--;
}
one = false;
while(it1 != N + 1 && (!one || profeet1.first < 0) ){
one = true;
profeet1.first += T * m - (lst[it1] - lst[it1 - 1]);
profeet1.second = min(profeet1.second,profeet1.first - T * m);
it1++;
}
int l = K;
int r = K;
while(l != 1 && r != N && cesh < 2 * lst[N]){
/*printf("%d %d %lld\n",l,r,cesh);
printf("%d %d\n",it,it1);
printf("%lld %lld\n",profeet.first,profeet.second);
printf("%d %d\n",profeet1.first,profeet1.second);
printf("\n");*/
if(cesh >= -min(profeet.second, profeet1.second)){
if(max(profeet.first, profeet1.first) < 0){
long long int num = 0;
if(profeet.second < profeet1.second){
while(num != profeet.second){
if(num == 0) num = lst[l - 1] - lst[l];
else num += T * m + lst[l - 1] - lst[l];
l--;
}
it = l - 1;
one = false;
profeet = {0,0};
while(it != 0 && (!one || profeet.first < 0) ){
one = true;
profeet.first += T * m - (lst[it + 1] - lst[it]);
profeet.second = min(profeet.second,profeet.first - T * m);
it--;
}
}
else{
while(num != profeet1.second){
if(num == 0) num = lst[r] - lst[r + 1];
else num += T * m + lst[r] - lst[r + 1];
r++;
}
it1 = r + 1;
one = false;
profeet1 = {0,0};
while(it1 != N + 1 && (!one || profeet1.first < 0) ){
one = true;
profeet1.first += T * m - (lst[it1] - lst[it1 - 1]);
profeet1.second = min(profeet1.second,profeet1.first - T * m);
it1++;
}
}
}
if(profeet.first > profeet1.first){
cesh += profeet.first;
l = it + 1;
one = false;
profeet = {0,0};
while(it != 0 && (!one || profeet.first < 0) ){
one = true;
profeet.first += T * m - (lst[it + 1] - lst[it]);
profeet.second = min(profeet.second,profeet.first - T * m);
it--;
}
}
else{
cesh += profeet1.first;
r = it1 - 1;
one = false;
profeet1 = {0,0};
while(it1 != N + 1 && (!one || profeet1.first < 0) ){
one = true;
profeet1.first += T * m - (lst[it1] - lst[it1 - 1]);
profeet1.second = min(profeet1.second,profeet1.first - T * m);
it1++;
}
}
}
else if(cesh < -max(profeet.second, profeet1.second)){
break;
}
else{
if(cesh >= -profeet.second){
cesh += profeet.first;
l = it + 1;
one = false;
profeet = {0,0};
while(it != 0 && (!one || profeet.first < 0) ){
one = true;
profeet.first += T * m - (lst[it + 1] - lst[it]);
profeet.second = min(profeet.second,profeet.first - T * m);
it--;
}
}
else{
cesh += profeet1.first;
r = it1 - 1;
one = false;
profeet1 = {0,0};
while(it1 != N + 1 && (!one || profeet1.first < 0) ){
one = true;
profeet1.first += T * m - (lst[it1] - lst[it1 - 1]);
profeet1.second = min(profeet1.second,profeet1.first - T * m);
it1++;
}
}
}
}
//printf("%d %d %d\n",l,r,cesh);
if(cesh < 2 * lst[N]){
if(l == 1){
while(r != N){
if(cesh >= lst[r + 1] - lst[r]){
cesh += T * m - (lst[r + 1] - lst[r]);
}
else break;
r++;
}
}
if(r == N){
while(l != 1){
if(cesh >= lst[l] - lst[l - 1]){
cesh += T * m - (lst[l] - lst[l - 1]);
}
else break;
l--;
}
}
}
m/= 2;
//printf("%d %d %d %lld\n\n",l,r,m,cesh);
if( cesh >= 2 * lst[N] || (l == 1 && r == N) ){
e = m;
}
else s = m + 1;
}
printf("%d\n",s);
}
