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#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

struct range {
    long long begin, end;
};

bool cmp(const range &a, const range &b) {
    if (a.begin < b.begin) return true;
    return false;
}

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

    long long n, m, s;
    cin >> n >> m >> s;

    vector<range> v(m);
    for (int i = 0; i < m; i++) {
        cin >> v[i].begin >> v[i].end;
    }
    
    sort(v.begin(), v.end(), cmp);
    
    vector<range> w;
    w.push_back(v[0]);
    for (int i = 1; i < m; i++){
        if (v[i - 1].end + 1 == v[i].begin) w[w.size() - 1].end = v[i].end;
        else w.push_back(v[i]);
    }
    
    long long dist = 1'000'000'000'000'000'000, building = -1;
    for (range &e : w) {
        if (e.begin <= s && s <= e.end) {
            long building_before = e.begin - 1;
            long building_after = e.end + 1;
            if (e.begin - 1 >= 1 && s - building_before < dist) {
                dist = s - building_before;
                building = building_before;
            }
            if (e.end + 1 <= n && building_after - s < dist) {
                dist = building_after - s;
                building = building_after;
            }
        }
    }
    cout << building << endl;

    return 0;
}