#include<bits/stdc++.h> using namespace std; int main(){ long long n,k; cin>>n>>k; long long a,b; vector<pair<long long,long long>> v; for(long long i=0;i<n;i++){ cin>>a>>b; v.push_back(make_pair(a,0)); v.push_back(make_pair(b,1)); } sort(v.begin(),v.end()); long long c=0; long long t=1; long long p=0; p=v[0].first; for(long long i=1;i<v.size();i++){ if(v[i].second==0){ c+=(v[i].first-p)*t; p=v[i].first-1; if(c>=k){ cerr<<i<<" "<<c<<" "<<t<<" "<<p<<endl; long long ans=p-(c-k)/t; cout<<ans<<endl; return 0; } t++; p=v[i].first; } else { c+=(v[i].first-p+1)*t; p=v[i].first; if(c>=k){ cerr<<i<<" "<<c<<" "<<t<<" "<<p<<endl; long long ans=p-(c-k)/t; cout<<ans<<endl; return 0; } t--; p=v[i].first+1; } cerr<<i<<" "<<c<<" "<<t<<" "<<p<<endl; } }