#include //#include using namespace std; //using namespace atcoder; //using mint = modint1000000007; //const int mod = 1000000007; //using mint = modint998244353; //const int mod = 998244353; const int INF = 1e9; //const long long LINF = 1e18; //const bool debug = false; #define rep(i, n) for (int i = 0; i < (n); ++i) #define rep2(i,l,r)for(int i=(l);i<(r);++i) #define rrep(i, n) for (int i = (n-1); i >= 0; --i) #define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i) #define all(x) (x).begin(),(x).end() #define allR(x) (x).rbegin(),(x).rend() #define endl "\n" #define P pair template inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; } template inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; } vectorp, q; int n, d; bool f(int x) { vector> dp(d, vector(n, -INF)); rep(i, n) if (-p[i] >= x)dp[0][i] = -p[i] + q[i]; rep(i, d - 1) { vectormaxL(n + 1, -INF), maxR(n + 1, -INF); rep(j, n)maxL[j + 1] = max(maxL[j], dp[i][j]); rep(j, n)maxR[j + 1] = max(maxR[j], dp[i][n - j - 1]); rep(j, n) { int mx = max(maxL[j], maxR[n - (j + 1)]); mx -= p[j]; if (mx >= x)dp[i + 1][j] = mx + q[j]; } } rep(i, n) if (-INF != dp[d - 1][i])return true; return false; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); cin >> n >> d; p.resize(n); q.resize(n); rep(i, n)cin >> p[i] >> q[i]; int ok = -INF - 1; int ng = INF + 1; while (1 < abs(ok - ng)) { int c = (ng + ok) / 2; if (f(c)) ok = c; else ng = c; } cout << ok << endl; return 0; }