#include<bits/stdc++.h> #define REP(i,n) for(int i=0;i<(n);i++) #define ALL(v) (v).begin(),(v).end() #define SZ(x) ((int)(x).size()) #define int long long using namespace std; typedef vector<int> vint; typedef pair<int,int> pint; int N,K; vint a,b; bool check(int x) {// x以下の数がK個数以上あるか int cnt=0; REP(i,N){ if(a[i]<=x and x<=b[i]) cnt+=x-a[i]+1; else if(b[i]<x) cnt+=b[i]-a[i]+1; } return cnt>=K; } signed main() { cin>>N>>K; a.resize(N); b.resize(N); REP(i,N) cin>>a[i]>>b[i]; int ng=0,ok=1e9; while(ok-ng>1){ int mid=(ok+ng)/2; if(check(mid)) ok=mid; else ng=mid; } cout<<ok<<endl; }