1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pii pair<int,int>
#define pl pair<ll,ll>
#define F first
#define S second
#define pq priority_queue
#define all(x) x.begin(), x.end()
#define deb(x) cout << #x << " = " << x << '\n';
#define deb2(x,y) cout << #x << " = " << x << ", " << #y << " = " << y << '\n';

constexpr ll M = 1e18+7;
constexpr int N = 1e6+7;
constexpr bool debug = 0;

map<ll,ll> taken;
vector<ll> cand;

int main(){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	ll n, m, s;
	cin >> n >> m >> s;
	for(int i = 0; i < m; i++){
		ll a, b; cin >> a >> b;
		taken[a] = taken[b] = 1;
		cand.pb(a-1); cand.pb(b+1);
	}
	ll best = M;
	ll bul = 0;
	sort(all(cand));
	for(auto k: cand){
		if(taken[k] != 1 && k >= 1 && k <= n && best > abs(s-k)){
			//deb2(k, abs(s-k));

			best = min(best,abs(s-k));
			bul = k;
		}
	}
	cout << bul << '\n';
	return 0;
}