#include #include using namespace atcoder; //#pragma GCC optimize ("O3") using namespace std; #define reps(i,s,n) for(int i = s; i < n; i++) #define rep(i,n) reps(i,0,n) #define Rreps(i,n,e) for(int i = n - 1; i >= e; --i) #define Rrep(i,n) Rreps(i,n,0) #define ALL(a) a.begin(), a.end() using ll = long long; using vec = vector; using mat = vector; ll N,M,H,W,Q,K,A,B; string S; using P = pair; using tp = tuple; const ll INF = (1LL<<60); template bool chmin(T &a, const T b){ if(a > b) {a = b; return true;} else return false; } template bool chmax(T &a, const T b){ if(a < b) {a = b; return true;} else return false; } template void my_printv(std::vector v,bool endline = true){ if(!v.empty()){ for(std::size_t i{}; i; int main() { cin.tie(nullptr); ios::sync_with_stdio(false); cin>>N>>K; vec p(N), q(N); rep(i, N) cin>>p[i]>>q[i]; const int st = (int)1e+8; auto ok = [&](int bd){ vec dp(N); rep(i, N){ if(st - p[i] < bd){ dp[i] = - INF; }else{ dp[i] = st - p[i]; } } rep(lp, K - 1){ vec ndp(N, -INF); rep(lp2, 2) { M = -INF; rep(tmp, N) { int i = (lp2 ? N - 1 - tmp : tmp); chmax(ndp[i], M); if (dp[i] - p[i] >= bd) chmax(M, dp[i] + q[i] - p[i]); } } dp = ndp; } return *max_element(ALL(dp)) != -INF; }; ll lb = 0, ub = st * 2; while(ub - lb > 1){ ll cen = lb + (ub - lb) / 2; (ok(cen) ? lb : ub) = cen; } cout<