#include //#include //#include //#include #define rep(i, a) for (int i = (int)0; i < (int)a; ++i) #define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i) #define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i) #define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i) #define pb push_back #define eb emplace_back #define all(x) x.begin(), x.end() #define rall(x) x.rbegin(), x.rend() #define popcount __builtin_popcount #define fi first #define se second using ll = long long; constexpr ll mod = 1e9 + 7; constexpr ll INF = 1LL << 60; // #pragma GCC target("avx2") // #pragma GCC optimize("O3") // #pragma GCC optimize("unroll-loops") //using lll=boost::multiprecision::cpp_int; //using Double=boost::multiprecision::number>;//仮数部が1024桁 template inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; } template inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; } template T mypow(T x, T n, const T &p = -1) { //x^nをmodで割った余り if(p!=-1){ x%=p; } T ret = 1; while (n > 0) { if (n & 1) { if (p != -1) ret = (ret * x) % p; else ret *= x; } if (p != -1) x = (x * x) % p; else x *= x; n >>= 1; } return ret; } using namespace std; //using namespace atcoder; void solve() { ll n,d; cin>>n>>d; vector>t(n,vector(2)); rep(i,n){ cin>>t[i][0]>>t[i][1]; } vector>dp(n+1,vector(2,-INF)); dp[0][0]=0; rep(i,n){ rep(j,2){ if(dp[i][j]==-INF)continue; chmax(dp[i+1][j],dp[i][j]+t[i][j]); chmax(dp[i+1][j^1],dp[i][j]-d+t[i][j^1]); } } cout<