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#include <bits/stdc++.h>
#define LL long long

using namespace std;

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    LL n, m, s;
    cin >> n >> m >> s;

    vector<pair<LL, LL>> seg(m);
    for (int i = 0; i < m; i++) {
        cin >> seg[i].first >> seg[i].second;
    }

    sort(seg.begin(), seg.end());
    
    LL curr = 0;
    LL ans = 1e12 + 7, min_dist = 1e12 + 7;
    for (int i = 0; i < m; i++) {
        if (seg[i].first - 1 > curr) {
            LL dist = abs(s - (seg[i].first - 1));
            if (dist == min_dist)
                ans = min(ans, seg[i].first - 1);
            else if (dist < min_dist) {
                ans = seg[i].first - 1;
                min_dist = dist;
            }
        }
        curr = seg[i].second; 
    }

    curr = n + 1;
    for (int i = m - 1; i >= 0; i--) {
        if (seg[i].second + 1 < curr) {
            LL dist = abs(s - (seg[i].second + 1));
            if (dist == min_dist)
                ans = min(ans, seg[i].second + 1);
            else if (dist < min_dist) {
                ans = seg[i].second + 1;
                min_dist = dist;
            }
        }
        curr = seg[i].first;
    }

    cout << ans << "\n";
}