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#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;

long long n, m, s;

vector<pair<long long, long long>>vec, vec2;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin>>n>>m>>s;
    long long a, b;
    for(int i=0; i<m; i++){
        cin>>a>>b;
        vec.push_back({a, b});
    }
    sort(vec.begin(), vec.end());
    vec2.push_back(vec[0]);
    for(int i=1; i<m; i++){
        if(vec[i].first == vec2.back().second+1){
            vec2.back().second = vec[i].second;
        }
        else{
            vec2.push_back(vec[i]);
        }
    }
    for(pair<long long, long long>p : vec2){
        if(p.first <= s && p.second >= s){
             if((s - p.first <= p.second - s && p.first > 1) || p.second == n){
                cout<<p.first-1;
             }
             else{
                cout<<p.second+1;
             }
        }
    }
    return 0;
}