import sys, heapq
def input():
	return sys.stdin.readline()[:-1]

n, k, q = map(int, input().split())
a = list(map(int, input().split()))
b = sorted(a)
a = [0] + a + [0]
ans = 10**30
for x in b:
	removed = []
	que = []
	for i in range(n+2):
		if a[i] < x:
			que = []
		else:
			heapq.heappush(que, a[i])
			if len(que) == k:
				removed.append(heapq.heappop(que))
	if len(removed) < q:
		continue
	removed.sort()
	ans = min(ans, removed[q-1] - x)
print(ans)