#include <stdio.h>
#define N 100000
#define N2 (N * 2 + 1)
#define N4 (N2 * 2)
#define INF 0x3f3f3f3f
long long min(long long a, long long b) { return a < b ? a : b; }
int solve(int *xx, int n, int s, int x) {
static long long aa[N2], bb[N2], aa_[N4], bb_[N4];
int na, nb, na_, nb_, r, i, ia, ib, j;
long long a, b, tmp;
na = 0;
aa[na++] = x;
for (i = s; i > 0; i--)
aa[na++] = -(xx[i] - xx[i - 1]), aa[na++] = x;
for (i = 1; i < na; i++)
aa[i] += aa[i - 1];
nb = 0;
bb[nb++] = 0;
for (i = s; i + 1 < n; i++)
bb[nb++] = -(xx[i + 1] - xx[i]), bb[nb++] = x;
for (i = 1; i < nb; i++)
bb[i] += bb[i - 1];
for (r = 0; r < 2; r++) {
i = 0, na_ = 0;
while (1) {
aa_[na_++] = aa[i];
j = i + 1, a = aa[i];
while (j < na && (r == 0 ? aa[j] <= aa[i] : aa[j] < aa[i]))
a = min(a, aa[j++]);
if (j == na)
break;
aa_[na_++] = a;
i = j;
}
i = 0, nb_ = 0;
while (1) {
bb_[nb_++] = bb[i];
j = i + 1, b = bb[i];
while (j < nb && (r == 0 ? bb[j] <= bb[i] : bb[j] < bb[i]))
b = min(b, bb[j++]);
if (j == nb)
break;
bb_[nb_++] = b;
i = j;
}
if (aa_[0] + bb_[0] < 0)
return 0;
ia = ib = 0;
while (ia + 2 < na_ || ib + 2 < nb_)
if (ia + 2 < na_ && aa_[ia + 1] + bb_[ib] >= 0)
ia += 2;
else if (ib + 2 < nb_ && aa_[ia] + bb_[ib + 1] >= 0)
ib += 2;
else
return 0;
for (i = 0, j = na - 1; i < j; i++, j--)
tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
for (i = 0, j = nb - 1; i < j; i++, j--)
tmp = bb[i], bb[i] = bb[j], bb[j] = tmp;
}
return 1;
}
int main() {
static int xx[N];
int n, s, t, i, lower, upper;
scanf("%d%d%d", &n, &s, &t), s--;
for (i = 0; i < n; i++)
scanf("%d", &xx[i]);
lower = -1, upper = INF;
while (upper - lower > 1) {
int v = (lower + upper) / 2;
if (solve(xx, n, s, min((long long) t * v * 2, INF)))
upper = v;
else
lower = v;
}
printf("%d\n", upper);
return 0;
}
