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
#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>
#include <ranges>


using namespace std;

int main()
{
    int64_t n, s;
    int m;
    cin>>n>>m>>s;

    vector <pair<int64_t, int64_t>> blocks;

    blocks.reserve(m);

    for (int i=0; i<m; i++){
        int64_t a,b;
        cin>>a>>b;
        blocks.push_back(make_pair( a,b ) );
    }
    blocks.push_back(make_pair( 0,0 ) );
    blocks.push_back(make_pair( n+1,n+1 ) );

    ranges::sort(blocks);

    int is=0;
    for (; is<blocks.size();is++){
        if (blocks[is].second >= s)
            break;
    }

    int64_t B=0,A=0;
    for (int i=is; i<blocks.size()-1;i++){
        if (blocks[i].second + 1 < blocks[i+1].first ){
            B = blocks[i].second + 1;
            break;
        }
    }
    for (int i=is; i>0; i--){
        if (blocks[i].first - 1 > blocks[i-1].second){
            A = blocks[i].first - 1;
            break;
        }
    }

   // cout<<A<<" "<<B<<endl;
    if (A==0)
        cout<<B<<endl;
    else if (B==0)
        cout<<A<<endl;
    else
        cout<<( (B-s < s-A)?B:A)<<endl;


    return 0;
}