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/*
 * Opis: Główny nagłówek
 */
#include<bits/stdc++.h>
using namespace std;
using LL=long long;
#define FOR(i,l,r)for(int i=(l);i<=(r);++i)
#define REP(i,n)FOR(i,0,(n)-1)
#define ssize(x)int(x.size())
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

const LL inf = 1e18;

void update(vector<pair<LL, LL>> &arr) {
	vector<pair<LL,LL>> temp;
	temp.push_back({0, 0});
	for (auto [a, b] : arr) {
		if (temp.back().second + 1 == a) {
			temp.back().second = b;
		}
		else {
			temp.push_back({a, b});
		}
	}
	swap(arr, temp);
}

int main() {
	cin.tie(0)->sync_with_stdio(0);
	LL n, s;
	int m;
	cin >> n >> m >> s;
	vector<pair<LL, LL>> arr(m);
	for (auto& [a, b] : arr) {
		cin >> a >> b;
	}
	sort(arr.begin(), arr.end());
	update(arr);
	LL res = inf;
	LL best = -1;
	for (auto [a, b] : arr) {
		if (a <= s && s <= b) {
			if (a > 1) {
				LL curr = min(res, abs(s - (a-1)));
				if (curr < res) {
					res = curr;
					best = a-1;
				}
			}
			if (b < n) {
				LL curr = min(res, abs(s - (b+1)));
				if (curr < res) {
					res = curr;
					best = b+1;
				}
			}
		}
	}
	cout << best << "\n";
}