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// Mateusz Kussowski
// PA 2025 day 2 C szkoła

#include <iostream>
#include <unordered_map>
using namespace std;

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

    long long n, m, s;
    cin >> n >> m >> s;
    unordered_map<long long, long long> adj;

    long long left_check = 0, right_check = 0;

    {
        long long a, b;
        for(int i = 0; i < m; ++i){
            cin >> a >> b;
            adj[a] = b;
            adj[b] = a;
            if(a <= s && s <= b){
                left_check = a - 1;
                right_check = b + 1;
            }
        }
    }

    while(left_check >= 1 && adj.count(left_check)){
        left_check = adj[left_check] - 1;
    }
    while(right_check <= n && adj.count(right_check)){
        right_check = adj[right_check] + 1;
    }

    pair<long long, long long> best = {1000000000000000, -1};

    if(left_check >= 1){
        best = min(best, {s - left_check, left_check});
    }
    if(right_check <= n){
        best = min(best, {right_check - s, right_check});
    }
    cout << best.second << "\n";
    return 0;
}