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


int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	LL n, m, s;
	cin>>n>>m>>s;
	vector<pair<LL, LL>> v(m);
	for(auto &[a, b] : v)cin>>a>>b;
	sort(v.begin(), v.end());
	set<LL> ss;
	for(auto [a, b] : v){ss.insert(a);ss.insert(b);}
	LL odl = 1000000000000001LL;
	LL id = 0;
	for(auto [a, b] : v){
		a--;b++;
		if(a > 0 && ss.find(a) == ss.end()){
			if(abs(s-a) < odl){
				id = a;
				odl = abs(s-a);
			}else if(abs(s-a) == odl){
				if(a < id)id=a;
			}
		}
		if(b <= n && ss.find(b) == ss.end()){
			if(abs(s-b) < odl){
				id = b;
				odl = abs(s-b);
			}else if(abs(s-b) == odl){
				if(b < id)id=b;
			}
		}
	}
	cout<<id<<"\n";
	return 0;
}