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// Witold Milewski
// PA 2025
#include <bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i=a; i<=b; ++i)
#define FORB(i, b, a) for(int i=b; i>=a; --i)
#define sz(A) (int)(A.size())
#define ll long long
#define eb emplace_back
#define pb push_back
#define pi pair<int, int>
#define f first
#define s second
#define rs resize
#define V vector

ll n, s;
int m;
pair<ll, ll> wyn;
map<ll, bool> zaj;

bool check(ll x) {
  if(zaj[x]==1) return 0;
  return (1<=x && x<=n);
}

void minimuj(ll x) {
  wyn=min(wyn, {abs(x-s), x});
}

signed main() {
  cin.tie(0) -> ios_base::sync_with_stdio(0);
  wyn = {1e18, 1e18};
  cin >> n >> m >> s;

  V<pair<ll, ll>> prz;

  ll l, r;
  FOR(i, 1, m) {
    cin >> l >> r;
    zaj[l]=1;
    zaj[r]=1;
    prz.pb({l, r});
  }

  for(auto [l, r] : prz) {
    if(check(l-1)) minimuj(l-1);
    if(check(r+1)) minimuj(r+1);
  }

  cout << wyn.s << '\n';
}