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#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll ans, idx = 1;

void f(ll val, ll i){
    if(ans > val || (ans == val && i < idx)){
        ans = val;
        idx = i;
    }
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    ll n, m, s;
    cin >> n >> m >> s;
    ans = n + 42;
    
    vector<pair<ll, ll>> intervals(m);
    for(int i = 0; i < m; i++){
        cin >> intervals[i].first >> intervals[i].second;
    }
    
    sort(intervals.begin(), intervals.end());
    
    for(int i = 0; i < m; i++){
        ll l = intervals[i].first, r = intervals[i].second;
        if(i != 0 && intervals[i - 1].second != l - 1) f(abs(s - l + 1), l - 1);
        else if(i == 0 && 1 <= l - 1) f(abs(s - l + 1), l - 1);
        if(i != m - 1 && r + 1 != intervals[i + 1].first) f(abs(r + 1 - s), r + 1);
        else if(i == m - 1 && r + 1 <= n) f(abs(r + 1 - s), r + 1);
    }
    cout << idx;
}