#include "bits/stdc++.h" using namespace std; typedef long long ll; #define INF (1<<30) #define INFLL (1ll<<30) typedef pair<int, int> P; typedef pair<int, P> E; #define MOD (1000000007ll) #define l_ength size void mul_mod(ll& a, ll b){ a *= b; a %= MOD; } void add_mod(ll& a, ll b){ a += b; a %= MOD; } ll cnt[225816],a[100100],b[100100]; vector<ll> v; int main(void){ int n,m,i; ll k; cin >> n >> k; --k; for(i=0; i<n; ++i){ cin >> a[i] >> b[i]; ++b[i]; v.push_back(a[i]); v.push_back(b[i]); } v.push_back(INFLL); sort(v.begin(),v.end()); for(i=0; i<n; ++i){ ++cnt[(int)(lower_bound(v.begin(),v.end(),a[i])-v.begin())]; --cnt[(int)(lower_bound(v.begin(),v.end(),b[i])-v.begin())]; } m = v.l_ength()-1; for(i=0; i<m; ++i){ cnt[i+1] += cnt[i]; } for(i=0; i<m; ++i){ if(v[i]==v[i+1]){ continue; } if(0<=k && k<cnt[i]*(v[i+1]-v[i])){ cout << (v[i]+k/cnt[i]) << endl; break; } k -= cnt[i]*(v[i+1]-v[i]); } return 0; }