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#include <stdio.h>
#include <time.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <map> 
#include <string>
#include <vector>  
#include <iostream> 
#include <sstream> 
#include <queue>
#include <algorithm>
#include <assert.h>


using namespace std;

#define ll long long
#define PB 		push_back
#define FOR(a,start,end) 	for(int a=int(start); a<int(end); a++)
#define INF 		INT_MAX
#define SORT(a) 	sort(a.begin(),a.end()) 
#define CL(a,x) 		memset(a,x,sizeof(a))
#define REP(a,x)	for(int a=0;a<x;a++)
#define REP1(a,x)	for(int a=1;a<=x;a++)
#define MP 		make_pair



typedef vector<ll>     vi;
typedef pair<ll, ll>     pii;
typedef vector<string> vs;
typedef vector<pii> vii;
typedef vector<vector<ll> > vvi;
typedef vector<vector<string> > vvs;
typedef vector<pair<string, string> > vss;
typedef pair<string, string> pss;
typedef pair<ll, pii> ppii;
typedef vector<ppii> vppii;
typedef vector<vector<pii> > vvii;
typedef vector<vvi> vvvi;


ll  n, k, q, d, t, g, b, z, p, a, c, m,s;

vi vk, va, vb, vc;
vvi vva, vvb, vvd, vva0;
vii vax,vbx;
vvii vvqx;
vs vw;
string w;

int main() {
	//freopen("c:\\wojtek\\uva\\pa\\debug\\t1.in", "rt", stdin);
	//freopen("c:\\cygwin64\\home\\plwokow\\.check_sol\\tel\\tel_n400\\tel1.in", "rt", stdin);
	//d = 1000000007;
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(NULL);
	//	while (1) {
	
		cin >> n>>m>>s;
		vax.clear(); vbx.clear();
		for (int i = 0; i < m; i++) {
			cin >> a>>b;
			vax.push_back(MP(a,b));
		}
		SORT(vax);
		vbx.push_back(vax[0]);
		int j = 0;
		for (int i = 1; i < m; i++) {
			if (vax[i].first == (vax[i - 1].second + 1)) {
				vbx[j].second = vax[i].second;
			}
			else {
				vbx.push_back(vax[i]);
				j++;
			}
		}
		z = -1;
		for (int i = 0; i < (int)vbx.size(); i++) {
			if ((s >= vbx[i].first) && (s <= vbx[i].second)) {
				if (vbx[i].first == 1)
					z = vbx[i].second + 1;
				else if (vbx[i].second==n) {
					z = vbx[i].first - 1;
				}
				else {
					if ((vbx[i].second - s) < (s - vbx[i].first)) {
						z= vbx[i].second + 1;
					}
					else {
						z = vbx[i].first - 1;
					}
				}
				break;
			}
		}
		
		cout << z << '\n';
	
	//}

	return 0;

}