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#include <bits/stdc++.h>

using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    long long n, s, result, id;
    int m;
    pair<long long, long long>* arr;
    
    cin >> n >> m >> s;
    
    arr = new pair<long long, long long>[m];
    
    for(int i = 0; i < m; ++i){
        cin >> arr[i].first >> arr[i].second;
    }
    
    sort(arr, arr + m);
    
    result = 1000000000000000;
    
    for(int i = 1; i < m - 1; ++i){
        if(arr[i].first - 1 > arr[i - 1].second){
            if(result > abs(arr[i].first - 1 - s)){
                result = abs(arr[i].first - 1 - s);
                id = arr[i].first - 1;
            }
        }
        if(arr[i].second + 1 < arr[i + 1].first){
            if(result > abs(arr[i].second + 1 - s)){
                result = abs(arr[i].second + 1 - s);
                id = arr[i].second + 1;
            }
        }
    }
    
    if(arr[0].first > 1){
        
        if(result > abs(arr[0].first - 1 - s)){
            result = abs(arr[0].first - 1 - s);
            id = arr[0].first - 1;
        }
    }
    
    if(arr[0].second < n && (m == 1 || arr[1].first - 1 > arr[0].second)){
        if(result > abs(arr[0].second + 1 - s)){
            result = abs(arr[0].second + 1 - s);
            id = arr[0].second + 1;
        }
    }
    
    if(arr[m - 1].first > 1 && (m == 1 || arr[m - 2].second + 1 < arr[m - 1].first)){
        if(result > abs(arr[m - 1].first - 1 - s)){
            result = abs(arr[m - 1].first - 1 - s);
            id = arr[m - 1].first - 1;
        }
    }
    
    if(arr[m - 1].second < n){
        if(result > abs(arr[m - 1].second + 1 - s)){
            result = abs(arr[m - 1].second + 1 - s);
            id = arr[m - 1].second + 1;
        }
    }
    
    cout << id ;
    
    delete [] arr;
    
    return 0;
}