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#include <iostream>
#include <unordered_set>
#include <set>
#include <cmath>
using namespace std;

long long n, s;
int m;

unordered_set<long long> occupaied;
set<long long> proposition;

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

    for (int i = 0; i < m; i++)
    {
        long long start, stop;
        cin >> start >> stop;

        occupaied.insert(start);
        occupaied.insert(stop);

        if (start-1 >= 1)
            proposition.insert(start-1);

        if (stop+1 <= n)
            proposition.insert(stop+1);
    }

    long long best_idx = 0;
    long long best_distance = 100000000000000;

    for (auto iter = proposition.begin(); iter != proposition.end(); ++iter)
    {
        long long current_location = *iter;
        if (occupaied.find(current_location) != occupaied.end())
            continue;

        long long distance = abs(current_location - s);

        if (distance < best_distance)
        {
            best_distance = distance;
            best_idx = current_location;
        }
    }

    cout << best_idx;



    return 0;
}