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#include <bits/stdc++.h>
using namespace std;
#define int long long
vector<pair<int,int>> v;
unordered_map<int,bool> um;
int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    long long n,m,s;
    cin >> n >> m >> s;
    for(int i = 0; i<m; i++){
        int a,b;
        cin >> a >> b;
        v.emplace_back(a,b);
        um[a] = true;
        um[b] = true;
    }
    sort(v.begin(),v.end());
    int best_left = 0;
    int best_right = LLONG_MAX;
    for(auto x : v){
        int left = x.first - 1;
        int right = x.second + 1;
        if(left < s and !um[left]){
            best_left = max(best_left, left);
        }
        if(right > s and !um[right]){
            best_right = min(best_right, right);
        }
    }
    if(best_right > n){
        best_right = LLONG_MAX;
    }
    if(best_left != 0 and s-best_left <= best_right-s){
        cout << best_left <<"\n";
    }else{
        cout << best_right << "\n";
    }
}