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

const int N = 1e6 + 5;

#define st first
#define nd second

typedef pair<int,int> pun;
typedef long long ll;

ll dist (ll pos, ll s) {
	return abs(s - pos);
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	ll n, m, s;
	cin >> n >> m >> s;
	vector<pair<ll, ll>> v;
	for (int i = 0; i < m; i ++) {
		ll a, b;
		cin >> a >> b;
		v.emplace_back(a, b);
	}
	sort(v.begin(), v.end());
	ll d = n + 1;
	ll ans = 0;
	ll prev = 0;
	for (auto p : v) {
		ll a = p.first;
		ll b = p.second;
//		cerr << a << " " << b << "\n";
		if (prev < a - 1) {
			if (d > dist(a - 1, s)) {
				ans = a-1;
				d = dist(a-1, s);
			}

			if (d > dist(prev + 1, s)) {
				ans = prev+1;
				d = dist(prev+1, s);
			}
		}
		prev = b;
	}
	if (prev < n) {
		if (d > dist(prev + 1, s)) {
			ans = prev + 1;
			d = dist(prev+1, s);
		}
	}
	cout << ans;	

}