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import sys

input = sys.stdin.readline
n, m, s = map(int, input().split())
tab = []
for _ in range(m):
  tab.append(tuple(map(int, input().split())))
tab.sort()
new_tab = [tab[0]]
for a, b in tab[1:]:
  if a == new_tab[-1][1] + 1:
    new_tab[-1] = (new_tab[-1][0], b)
  else:
    new_tab.append((a, b))

# print(tab)
# print(new_tab)
best, where = 10**15, -1
for a, b in new_tab:
  if a > 1:
    if abs(s - (a - 1)) < best:
      best = abs(s - (a - 1))
      where = a - 1
  if b < n:
    if abs(s - (b + 1)) < best:
      best = abs(s - (b + 1))
      where = b + 1
print(where)