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
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
#include <bits/stdc++.h>
using namespace std;

#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

using segment_t = pair<long long, long long>;

vector<segment_t> merge_segments(vector<segment_t> segments) {
	int m = ssize(segments);
	vector<segment_t> ret;

	sort(segments.begin(), segments.end());
	segment_t current = segments[0];
	FOR (i, 1, m - 1) {
		auto [l1, r1] = current;
		auto [l2, r2] = segments[i];

		if (r1 + 1 == l2)
			current = {l1, r2};
		else {
			ret.emplace_back(current);
			current = {l2, r2};
		}
	}

	ret.emplace_back(current);
	return ret;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	long long n, s;
	int m;

	cin >> n >> m >> s;

	vector<segment_t> segments(m);
	REP (i, m) {
		long long l, r;
		cin >> l >> r;
		segments[i] = {l, r};
	}

	segments = merge_segments(segments);
	debug(segments);

	pair<long long, long long> answer = {LLONG_MAX, -1};
	for (auto [l, r] : segments) {
		if (l <= s and s <= r) {
			long long left = l - 1;
			if (left >= 1)
				answer = min(answer, {abs(s - left), left});

			long long right = r + 1;
			if (right <= n)
				answer = min(answer, {abs(s - right), right});

			break;
		}
	}

	debug(answer);
	cout << answer.second << '\n';
}