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

#define int long long 

int n, m, s;
vector<pair<int, int>> v;

pair<int, int> ans = {1e18, -1};

void check(int x){
	if(x == 0 || x == n+1) return;
	if(ans.first > abs(s-x)){
		ans = {abs(s-x), x};
	}
}	

signed main(){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	
	cin >> n >> m >> s;
	
	for(int i=0; i<m; i++){
		int a, b;
		cin >> a >> b;
		v.push_back({a,b});
	}
	
	sort(v.begin(), v.end());
	
	for(int i=0; i<v.size(); i++){
		int a = v[i].first, b = v[i].second;
		if(i == 0 || v[i-1].second < a-1) check(a-1);
		if(i+1 == m || v[i+1].first > b+1) check(b+1);
	}
	
	cout << ans.second << '\n';
	
	return 0;
}