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#include <bits/stdc++.h>

using namespace std;

#define ll long long

#define rng(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,b) rng(i,0,b)

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;

typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;

typedef pair<int,int> ii;

template<class t> using vc=vector<t>;
template<class t> using vvc=vc<vc<t>>;

const int MOD = 998244353;

ll read(){
    ll i;
    cin>>i;
    return i;
}

vi readvi(int n,int off=0,int shift=0){
    vi v(n+shift);
    rep(i,shift)v[i]=0;
    rep(i,n)v[i+shift]=read()+off;
    return v;
}

void YesNo(bool condition, bool do_exit=true) {
    if (condition)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
    if (do_exit)
        exit(0);
}

int main(void ) {
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    ll n,m,s;

    cin >> n >> m >> s;

    vl a;

    rep(i,m) {
        ll x, y;
        cin >> x >> y;
        a.push_back(x);
        a.push_back(y);
    }

    sort(a.begin(), a.end());

    int ind;
    for (ind = 0; ind < m; ++ind)
        if (s >= a[2*ind] and s <= a[2*ind+1])
            break;

    int left = ind;
    while (left > 0 and a[2*left] == a[2*(left-1)+1] + 1)
        --left;

    int right = ind;
    while (right < m-1 and a[2*right+1] == a[2*(right+1)] - 1)
        ++right;

    ll dist = 1e14;
    ll res = -1;

    if (a[2*left]-1 >= 1) {
        dist = s - (a[2 * left] - 1);
        res = a[2 * left] - 1;
    }

    if (a[2*right+1]+1 <= n and a[2 * right + 1] + 1 - s < dist) {
        dist = a[2 * right + 1] + 1 - s;
        res = a[2*right+1]+1;
    }

    cout << res << endl;

    return 0;
}