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
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
#include <bits/stdc++.h>
#include <iostream>
#include <vector>

using namespace std;

int find_range_index(const std::vector<std::pair<long long, long long>>& vec, long long s) {
    for (size_t i = 0; i < vec.size(); i++) {
        if (s >= vec[i].first && s <= vec[i].second) { 
            return i; 
        }
    }
    return -1; 
}

long long max(long long a, long long b) {
    return (a > b) ? a : b;
}

long long min(long long a, long long b) {
    return (a < b) ? a : b;
}

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

    long long n;
    int m;
    long long s;

    cin >> n;
    cin >> m;
    cin >> s;

    vector<pair<long long, long long>> ranges;

    long long a, b;
    for (int i = 0; i < m; i++) {
        cin >> a;
        cin >> b;
        ranges.push_back(pair(a, b));
    }
    
    sort(ranges.begin(), ranges.end());

    /*for (int i = 0; i < m; i++) {
        cout << ranges[i].first << "," << ranges[i].second << " ; ";
    }
    cout << endl;*/

    int position = find_range_index(ranges, s);

    //cout << "position = " << position << endl;

    long long min_dist = 1000000000001L;
    long long min_val = -1L;

    for (int i = position; i < m - 1; i++) {
        //cout << "Analyzing positions type 1: " << i << " " << i + 1 << endl;
        if (ranges[i + 1].first - ranges[i].second > 1L) {
            if (ranges[i].second + 1L - s < min_dist) {
                min_dist = ranges[i].second + 1L - s;
                min_val = ranges[i].second + 1L;
                //cout << "found " << min_dist << " " << min_val << endl;
                break;
            }
        }
    }

    if (ranges[m - 1].second < n && ranges[m - 1].second + 1L - s < min_dist) {
        min_dist = ranges[m - 1].second + 1L - s;
        min_val = ranges[m - 1].second + 1L;
    }

    for (int i = position; i > 0; i--) {
        //cout << "Analyzing positions type 2: " << i << " " << i + 1 << endl;
        if (ranges[i].first - ranges[i - 1].second > 1L) {
            if (s - (ranges[i].first - 1L) <= min_dist) {
                min_dist = s - (ranges[i].first - 1L);
                min_val = ranges[i].first - 1L;
                //cout << "found " << min_dist << " " << min_val << endl;
                break;
            }
        }
    }

    if (ranges[0].first > 1 && s - (ranges[0].first - 1L) <= min_dist) {
        min_dist = s - (ranges[0].first - 1L);
        min_val = ranges[0].first - 1L;
    }

    cout << min_val;

    return 0;
}