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
48
49
50
51
52
53
54
55
56
#include <bits/stdc++.h>
#define e using u=ostream;template<class a,class b>u&operator<<(u&o,pair<a,b>&x)
using namespace std;e;u&operator<<(u&o,string&s){return o<<s.c_str();}template<
class t>auto operator<<(u&o,t&x)->decltype(x.end(),o){o<<'{';int i=2;for(auto y:
x)o<<", "+i<<y,i=0;return o<<'}';}e{return o<<'('<<x.first<<", "<<x.second<<')';}
#ifdef DEBUG
#define LOG(x...)cerr<<"["#x"]: ",[](auto...$){((cerr<<$<<"; "),...)<<'\n';}(x)
#else
#define LOG(...)
#endif
#define ff first
#define ss second
#define ll long long

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	ll n;
	int m;
	ll s;
	cin >> n >> m >> s;
	vector <pair <ll, ll> > v(m);
	for (int i = 0; i < m; i++) {
		ll a; ll b;
		cin >> a >> b;
		v[i] = {a, b};
	}
	sort(v.begin(), v.end());
	int k = 0;
	while (v[k].ss < s) {
		k++;
	}
//	cout << k << " " ;
	int left = k;
	int right = k;
	while (left > 0 && v[left].ff-1 == v[left-1].ss) {
		left--;
	}
//	cout << left << " ";
	while (right < m-1 && v[right].ss+1 == v[right+1].ff) {
		right++;
	}
//	cout << right << " ";
	ll best = n;
	if (v[right].ss+1 <= n) {
		best = min(best, v[right].ss+1 - s);
//		cout << best << " ";
	}
	if (v[left].ff-1 > 0) {
		if (s - (v[left].ff-1) <= best) {
			cout << v[left].ff-1 << "\n";
			return 0;
		}
	}
	cout << v[right].ss+1 << "\n";
}