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#include<bits/stdc++.h>
#define FOR(i,a,b) for(int i=a;i<b;++i)
#define FORD(i,a,b) for(int i=a;i>=b;--i)
#define PB push_back
#define EB emplace_back
#define FI first
#define SE second
#define umap unordered_map
#define uset unordered_set
#define vi vector<int>
#define vvi vector<vi>
#define vll vector<ll>
#define vvll vector<vll>
#define vpii vector<pii>
#define pii pair<ll, ll>
#define pll pair<ll, ll>
#define ALL(X) (X).begin(),(X).end()
#ifndef DEBUG
#define endl (char)10
#endif
using namespace std;
using ll = long long;
using ld = long double;

template <class T>
ostream& operator<< (ostream& os, vector<T>& vec){
    for(auto& t : vec) os << t << " ";
    return os;
}
template<class T, class U>
ostream& operator<< (ostream& os, const pair<T, U>& p){
    os << p.FI << " " << p.SE;
    return os;
}
template<class T, class U>
istream& operator>> (istream& is, pair<T, U>& p){
    is >> p.FI >> p.SE;
    return is;
}
template <class T>
istream& operator>> (istream& is, vector<T>& vec){
    for(auto& p : vec) is >> p;
    return is;
}


int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    ll n, s;
    int m;
    cin >> n >> m >> s;
    vpii V(m);
    cin >> V;
    sort(ALL(V));
    int gdzie = 0;
    while(V[gdzie].FI > s || V[gdzie].SE < s) gdzie++;
    ll dol = V[gdzie].FI - 1, gora = V[gdzie].SE + 1;
    FORD(i,gdzie-1,0) {
		if (dol == V[i].SE) dol = V[i].FI - 1;
		else break;
    }
    FOR(i,gdzie+1,m) {
		if (gora == V[i].FI) gora = V[i].SE + 1;
		else break;
    }
    //cout << dol << " " << gora << endl;
    if(dol == 0) {
		cout << gora << endl;
    } else if(gora == n + 1) {
		cout << dol << endl;
    } else if (gora - s < s - dol) {
		cout << gora << endl;
    } else {
		cout << dol << endl;
    }
}