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#include<bits/stdc++.h>
using namespace std;

typedef pair<long long, long long> par;
vector<par> v;

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    long long n, m, s, a, b, wyn = -1;
    cin>>n>>m>>s;
    v.push_back(par(0, 0));
    v.push_back(par(n+1, n+1));
    for(int i=1; i<=m; i++) {
        cin>>a>>b;
        v.push_back(par(a, b));
    }
    sort(v.begin(), v.end());
    for(int i=1; i<v.size()-1; i++) {
        if(v[i].first - 1 > v[i-1].second) {
            a = v[i].first - 1;
            if(wyn == -1 || abs(s - a) < abs(s - wyn)) wyn = a;
        }
        if(v[i].second + 1 < v[i+1].first) {
            a = v[i].second + 1;
            if(wyn == -1 || abs(s - a) < abs(s - wyn)) wyn = a;
        }
    }
    cout<<wyn;
    return 0;
}