#include using namespace std; typedef long long signed int LL; typedef long long unsigned int LU; #define incII(i, l, r) for(int i = (l) ; i <= (r); ++i) #define incID(i, l, r) for(int i = (l) ; i < (r); ++i) #define decII(i, l, r) for(int i = (r) ; i >= (l); --i) #define decID(i, l, r) for(int i = (r) - 1; i >= (l); --i) #define inc(i, n) incID(i, 0, n) #define inc1(i, n) incII(i, 1, n) #define dec(i, n) decID(i, 0, n) #define dec1(i, n) decII(i, 1, n) #define inII(v, l, r) ((l) <= (v) && (v) <= (r)) #define inID(v, l, r) ((l) <= (v) && (v) < (r)) #define PB push_back #define EB emplace_back #define MP make_pair #define FI first #define SE second #define ALL(v) v.begin(), v.end() #define RALL(v) v.rbegin(), v.rend() template bool setmin (T & a, T b) { if(b < a) { a = b; return true; } else { return false; } } template bool setmax (T & a, T b) { if(b > a) { a = b; return true; } else { return false; } } template bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } } template bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } } LL mo(LL a, LL b) { assert(b > 0); a %= b; if(a < 0) { a += b; } return a; } LL fl(LL a, LL b) { assert(b > 0); return (a > 0 ? a / b : (a - b + 1) / b); } LL ce(LL a, LL b) { assert(b > 0); return (a < 0 ? a / b : (a + b - 1) / b); } #define bit(b, i) (((b) >> (i)) & 1) #define BC __builtin_popcountll #define SC(T, v) static_cast(v) #define SI(v) SC(int, v.size()) #define SL(v) SC( LL, v.size()) #define RF(e, v) for(auto & e: v) #define ei else if #define UR assert(false) // ---- ---- int n, k, a[100000], b[100000]; bool f(int x) { int s = 0; inc(i, n) { s += max(0, min(b[i], x) - a[i] + 1); } return (s >= k); } int main() { cin >> n >> k; inc(i, n) { cin >> a[i] >> b[i]; } int L = 0, H = 1e9 + 1; while(H - L > 1) { int M = (L + H) / 2; (f(M) ? H : L) = M; } cout << H << endl; return 0; }