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

constexpr int MAX_M = 1e3;

long long n, s;
int m; pair<long long, long long> seg[MAX_M + 2];

long long dist(long long p) {
    return llabs(s - p);
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    cin >> n >> m >> s;

    for(int i = 1; i <= m; i++) {
        cin >> seg[i].first >> seg[i].second;
    }

    seg[0] = {0, 0};
    seg[m + 1] = {n + 1, n + 1};

    sort(seg + 1, seg + 1 + m);

    long long ans = LLONG_MAX, best = -1;

    for(int i = 1; i <= m; i++) {
        if(seg[i - 1].second < seg[i].first - 1LL) {
            long long d = dist(seg[i].first - 1LL);

            if(d < ans) {
                ans = d;
                best = seg[i].first - 1LL;
            }
        }

        if(seg[i].second + 1LL < seg[i + 1].first) {
            long long d = dist(seg[i].second + 1LL);

            if(d < ans) {
                ans = d;
                best = seg[i].second + 1LL;
            }
        }
    }

    cout << best;
}