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#include <bits/stdc++.h>
#define st first
#define sc second
using namespace std;
typedef long long ll;
ll N, M, S;
vector< pair< ll, ll > > vec;

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);

    cin >> N >> M >> S;
    bool ok = 0;
    for(int i = 0; i < M; i++){
        ll l, r;
        cin >> l >> r;
        vec.push_back({l, r});
        if( S >= l && S <= r) ok = 1;
    }
    vec.push_back({0,0});
    vec.push_back({N+1, N+1});
    M+=2;
    if(!ok){ vec.push_back({S, S}); M++; }

    sort(vec.begin(), vec.end());
    ll x;
    for(int i = 0; i < M; i++){
        if( S >= vec[i].st && S <= vec[i].sc ){
            x = i;
            break;
        }
    }
    ll odp1 = -1;
    for(int i = x+1; i < M; i++){
        if( vec[i-1].sc+1 < vec[i].st ){
            odp1 = vec[i-1].sc+1;
            break;
        }
    }
    ll odp2 = -1;
    for(int i = x-1; i >= 0; i--){
        if( vec[i].sc < vec[i+1].st-1 ){
            odp2 = vec[i+1].st-1;
            break;
        }
    }
    if(odp1 == -1){ cout << odp2; }
    else if(odp2 == -1){ cout << odp1; }
    else if(odp1-S < S-odp2){ cout << odp1; }
    else{ cout << odp2; }
    return 0;
}