#include #define all(v) v.begin(), v.end() #define rall(v) v.rbegin(), v.rend() #define rep(i,n) for(int i=0;i<(int)(n);i++) #define drep(i,j,n) for(int i=0;i<(int)(n-1);i++)for(int j=i+1;j<(int)(n);j++) #define trep(i,j,k,n) for(int i=0;i<(int)(n-2);i++)for(int j=i+1;j<(int)(n-1);j++)for(int k=j+1;k<(int)(n);k++) #define codefor int test;scanf("%d",&test);while(test--) #define INT(...) int __VA_ARGS__;in(__VA_ARGS__) #define LL(...) ll __VA_ARGS__;in(__VA_ARGS__) #define yes(ans) if(ans)printf("yes\n");else printf("no\n") #define Yes(ans) if(ans)printf("Yes\n");else printf("No\n") #define YES(ans) if(ans)printf("YES\n");else printf("NO\n") #define popcount(v) __builtin_popcount(v) #define vector2d(type,name,h,...) vector>name(h,vector(__VA_ARGS__)) #define vector3d(type,name,h,w,...) vector>>name(h,vector>(w,vector(__VA_ARGS__))) #define umap unordered_map #define uset unordered_set using namespace std; using ll = long long; const int MOD=1000000007; const int MOD2=998244353; const int INF=1<<30; const ll INF2=1LL<<60; //入力系 void scan(int& a){scanf("%d",&a);} void scan(long long& a){scanf("%lld",&a);} templatevoid scan(pair& p){scan(p.first);scan(p.second);} templatevoid scan(tuple& p){scan(get<0>(p));scan(get<1>(p));scan(get<2>(p));} template void scan(T& a){cin>>a;} template void scan(vector& vec){for(auto&& it:vec)scan(it);} void in(){} template void in(Head& head, Tail&... tail){scan(head);in(tail...);} //出力系 void print(const int& a){printf("%d",a);} void print(const long long& a){printf("%lld",a);} void print(const double& a){printf("%.15lf",a);} templatevoid print(const pair& p){print(p.first);putchar(' ');print(p.second);} template void print(const T& a){cout< void print(const vector& vec){if(vec.empty())return;print(vec[0]);for(auto it=vec.begin();++it!= vec.end();){putchar(' ');print(*it);}} void out(){putchar('\n');} template void out(const T& t){print(t);putchar('\n');} template void out(const Head& head,const Tail&... tail){print(head);putchar(' ');out(tail...);} //デバッグ系 template void dprint(const T& a){cerr< void dprint(const vector& vec){if(vec.empty())return;cerr< void debug(const T& t){dprint(t);cerr< void debug(const Head& head, const Tail&... tail){dprint(head);cerr<<" ";debug(tail...);} ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; } ll modpow(ll a, ll b, ll p){ ll ans = 1; while(b){ if(b & 1) (ans *= a) %= p; (a *= a) %= p; b /= 2; } return ans; } ll modinv(ll a, ll m) {ll b = m, u = 1, v = 0;while (b) {ll t = a / b;a -= t * b; swap(a, b);u -= t * v; swap(u, v);}u %= m;if (u < 0) u += m;return u;} ll updivide(ll a,ll b){return (a+b-1)/b;} template void chmax(T &a,const T b){if(b>a)a=b;} template void chmin(T &a,const T b){if(b x(n); map>> Map; rep(i,n){ in(x[i]); Map[x[i]%d].emplace_back(x[i]+d*t,x[i]-d*t); } ll ans=0,l,r,ro; for(auto vec:Map){ ro=-INF2; sort(all(vec.second)); for(auto p:vec.second){ tie(r,l)=p; if(l>ro)ans+=(r-l)/d+1; else ans+=(r-ro)/d; ro=r; } } out(ans); }