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#include<bits/stdc++.h> 

using namespace std; 

typedef long long ll; 
#define st first 
#define nd second
vector<pair<ll, ll> > V; 
  
ll mabs(ll x) {
    if(x < 0) 
        return -x; 
    return x; 
}

const ll INF = (ll)1e18 + (ll)1234; 
int main(){ 
    ll n, m, s; 
    cin >> n >> m >> s; 
    ll li, ri; 
    for(int i = 0; i < m; i++){  
        cin >> li >> ri; 
        V.push_back({li, ri}); 
    }
    ll bestziom = -3; 
    sort(V.begin(), V.end());   
    ll minres = INF; 
    if(V[0].st > 1){ 
       if( minres > mabs(s-(V[0].st-1))){ 
            bestziom = V[0].st-1;  
            minres = mabs(s-(V[0].st -1)); 
       } 
    }
    for(int i = 0; i < V.size() -1; i++){ 
        if(V[i].nd + 1 == V[i+1].st) 
            continue; 
        //minres = min(minres, mabs(s - (V[0].nd + 1)));  
        if(minres > mabs(s - (V[i].nd+1))){ 
            minres = mabs(s - (V[i].nd + 1)); 
            bestziom = V[i].nd + 1; 
        }
        //minres = min(minres, mabs(s - (V[i+1].st -1))); 
        if(minres > mabs(s - (V[i+1].st -1))){ 
            minres = mabs(s - (V[i+1].st -1)); 
            bestziom = V[i+1].st -1; 
        }
    }
    if(V.back().nd < n){ 
        if(minres >mabs(s - (V.back().nd+1)) ){
            minres = mabs(s - (V.back().nd+1)) ; 
            bestziom = V.back().nd + 1; 
        }
    }
    cout << bestziom << "\n"; 
}