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#include <bits/stdc++.h>
using namespace std;

#define loop(i, a, b) for(int i = a; i <= b; i++)
#define all(x) x.begin(), x.end()
#define pb push_back
using ll = int64_t;

int main() {
  cin.tie(0)->sync_with_stdio(0);
  ll m; cin >> m;
  int n; cin >> n;
  ll s; cin >> s;

  vector<pair<ll, ll>> ranges;
  map<ll, int> used;

  loop(i, 1, n) {
    ll a, b; cin >> a >> b;
    ranges.pb({ a, b });
    used[a] = used[b] = 1;
  }

  sort(all(ranges));

  ll res = 1e18;

  for(auto [ a, b ] : ranges) {
    for(ll coord : { a-1, b+1 }) {
      if(coord < 1 || coord > m) continue;
      if(used[coord]) continue;
      if(abs(s - coord) < abs(s - res)) {
        res = coord;
      }
    }
  }

  cout << res << '\n';

}