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#include <bits/stdc++.h>
#define ll long long
using namespace std;

const ll INF = 1000000000100;

ll n, s;
int m;
vector<pair<ll, ll>> taken;

int findSchoolPrzedzial()
{
    int l = 0; 
    int r = m - 1;
    while(l < r)
    {
        int mid = (l + r) / 2;

        if(taken[mid].first <= s && s <= taken[mid].second)
            return mid;
        if(s < taken[mid].first)
            r = mid - 1;
        else
            l = mid + 1;
    }
    return l;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m >> s;
    taken.resize(m);
    for(int i = 0; i < m; i++)
    {   
        ll a, b;
        cin >> a >> b;
        taken[i] = { a, b };
    }
    sort(taken.begin(), taken.end());

    int idx = findSchoolPrzedzial();

    ll closestLeft = -INF;
    for(int i = idx; i > 0; i--)
    {
        if(taken[i].first - 1 > taken[i - 1].second)
        {
            closestLeft = taken[i].first - 1;
            break;
        }
    }
    if(closestLeft == -INF && taken[0].first > 1)
        closestLeft = taken[0].first - 1;


    ll closestRight = INF;
    for(int i = idx; i < m - 1; i++)
    {
        if(taken[i].second + 1 < taken[i + 1].first)
        {
            closestRight = taken[i].second + 1;
            break;
        }
    }
    if(closestRight == INF && taken[m - 1].second < n)
        closestRight = taken[m - 1].second + 1;

    ll diffLeft = s - closestLeft;
    ll diffRight = closestRight - s;

    if(closestLeft == -INF)
        cout << closestRight;
    else if(closestRight == INF)
        cout << closestLeft;
    else if(diffLeft <= diffRight)
        cout << closestLeft;
    else    
        cout << closestRight;

    return 0;
}