1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) int((x).size())
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

#ifdef LOCAL
auto operator<<(auto& o, auto x) -> decltype(x.first, o);
auto operator<<(auto& o, auto x) -> decltype(x.end(), o) {
  o << "{";
  for (int i = 0; auto y : x) o << ", " + !i++ * 2 << y;
  return o << "}"; }
auto operator<<(auto& o, auto x) -> decltype(x.first, o) {
  return o << "(" << x.first << ", " << x.second << ")"; }
void __print(auto... x) { ((cerr << x << " "), ...) << endl; }
#define debug(x...) __print("[" #x "]:", x)
#else
#define debug(...) 2137
#endif

int main() {
  cin.tie(0)->sync_with_stdio(0);

  ll n, m, s;
  cin >> n >> m >> s;
  vector<pair<ll, ll>> v;
  for(int i = 0; i < m; i++) {
    ll l, r;
    cin >> l >> r;
    v.push_back({l, r});
  }
  sort(all(v));
  vector<pair<ll, ll>> vv;
  for(auto [l, r] : v) {
    if(vv.size() && vv.back().second == l - 1) {
      auto [lt, rt] = vv.back();
      vv.pop_back();
      l = lt;
    }
    vv.push_back({l, r});
  }
  ll ans = -1, mn = 1e18;
  auto check = [&](ll x) {
    if(x < 1 || x > n) return;
    if(abs(x - s) < mn) {
      mn = abs(x - s);
      ans = x;
    }
  };
  for(auto [l, r] : vv) {
    check(l - 1);
    check(r + 1);
  }
  cout << ans << endl;
}