#pragma region template #pragma GCC optimize("Ofast") #include using namespace std; using ll=long long; using ld=long double; using vi=vector; using vll=vector; using pi=pair; using pll=pair; #define overload2(a,b,c,...) c #define overload3(a,b,c,d,...) d #define overload4(a,b,c,d,e,...) e #define overload5(a,b,c,d,e,f,...) f #define TYPE1(T) template #define TYPE2(T,U) template #define TYPE(...) overload2(__VA_ARGS__,TYPE2,TYPE1)(__VA_ARGS__) #define TYPES1(T) template #define TYPES2(H,T) template #define TYPES(...) overload2(__VA_ARGS__,TYPES2,TYPES1)(__VA_ARGS__) #define REP4(i,s,n,d) for(int i=(s);i<(n);i+=(d)) #define REP3(i,s,n) REP4(i,s,n,1) #define REP2(i,n) REP3(i,0,n) #define REP1(n) REP2(tomato,n) #define REP(...) overload4(__VA_ARGS__,REP4,REP3,REP2,REP1)(__VA_ARGS__) #define RREP4(i,n,s,d) for(int i=(n)-1;i>=s;i-=d) #define RREP3(i,n,s) RREP4(i,n,s,1) #define RREP2(i,n) RREP3(i,n,0) #define RREP1(n) RREP2(tomato,n) #define RREP(...) overload4(__VA_ARGS__,RREP4,RREP3,RREP2,RREP1)(__VA_ARGS__) #define FOR4(a,b,c,d,v) for(auto [a,b,c,d]:v) #define FOR3(a,b,c,v) for(auto [a,b,c]:v) #define FOR2(a,b,v) for(auto [a,b]:v) #define FOR1(a,v) for(auto a:v) #define FOR(...) overload5(__VA_ARGS__,FOR4,FOR3,FOR2,FOR1)(__VA_ARGS__) #define AFOR4(a,b,c,d,v) for(auto&[a,b,c,d]:v) #define AFOR3(a,b,c,v) for(auto&[a,b,c]:v) #define AFOR2(a,b,v) for(auto&[a,b]:v) #define AFOR1(a,v) for(auto&a:v) #define AFOR(...) overload5(__VA_ARGS__,AFOR4,AFOR3,AFOR2,AFOR1)(__VA_ARGS__) #define CFOR4(a,b,c,d,v) for(const auto&[a,b,c,d]:v) #define CFOR3(a,b,c,v) for(const auto&[a,b,c]:v) #define CFOR2(a,b,v) for(const auto&[a,b]:v) #define CFOR1(a,v) for(const auto&a:v) #define CFOR(...) overload5(__VA_ARGS__,CFOR4,CFOR3,CFOR2,CFOR1)(__VA_ARGS__) #define ALL(v) v.begin(),v.end() #define RALL(v) v.rbegin(),v.rend() #define SORT(v) sort(ALL(v)) #define RSORT(v) sort(RALL(v)) #define REVERSE(v) reverse(ALL(v)) #define UNIQUE(v) SORT(v),v.erase(unique(ALL(v)),v.end()) TYPES(T) void input(T&... a){ (cin>>...>>a); } #define DECLARE(T,...) T __VA_ARGS__;input(__VA_ARGS__); #define INT(...) DECLARE(int,__VA_ARGS__) #define STR(...) DECLARE(string,__VA_ARGS__) #define LL(...) DECLARE(long long,__VA_ARGS__) #define CHR(...) DECLARE(char,__VA_ARGS__) #define DBL(...) DECLARE(double,__VA_ARGS__) #define VI(n,v) vi v(n);cin>>v; #define VLL(n,v) vll v(n);cin>>v; TYPE(T) istream&operator>>(istream&is,vector&v){ for(auto&a:v)cin>>a; return is; } TYPE(T) ostream&operator<<(ostream&os,const vector&v){ if(&os==&cerr)os<<"["; REP(i,v.size()){ os<>(istream&is,pair&p){ cin>>p.first>>p.second; return is; } #ifdef __LOCAL #include #else #define debug(...) void(0) #endif void print(){ cout << '\n'; } TYPES(T,Ts) void print(const T& a,const Ts&... b){ cout<; TYPE(T) using pqg=priority_queue,greater>; TYPE(T) T pick(queue& que){assert(que.size()); T a=que.front();que.pop();return a;} TYPE(T) T pick(pq& que){assert(que.size()); T a=que.top();que.pop();return a;} TYPE(T) T pick(pqg& que){assert(que.size()); T a=que.top();que.pop();return a;} TYPE(T) T pick(stack& sta){assert(sta.size()); T a=sta.top();sta.pop();return a;} string YES(bool f=true){return (f?"YES":"NO");} string Yes(bool f=true){return (f?"Yes":"No");} string yes(bool f=true){return (f?"yes":"no");} constexpr int INF=1e9+7; constexpr ll LINF=ll(1e18)+7; constexpr ld EPS=1e-10; vi iota(int n){vi a(n);iota(ALL(a),0);return a;} TYPE(T) vector> query_sort(const vector&v){ vector> res(v.size()); REP(i,v.size())res[i]={v[i],i}; SORT(res); return res; } TYPE(T) T rev(T a){ REVERSE(a);return a; } TYPE(T) void fin(T a){cout<b&&(a=b,true));} TYPES(T,Ns) auto make_vector(T x,int n,Ns ...ns){ if constexpr(sizeof...(ns)==0)return vector(n,x); else return vector(n,make_vector(x,ns...)); } bool in(const ll S,const int a){return (S>>a)&1;} int popcount(const ll S){return __builtin_popcountll(S);} int digit(char c){ return (c>='0' and c<='9' ? c-'0' : -1);} #pragma endregion template #include using namespace atcoder; using mint=modint1000000007; ostream& operator<<(ostream &os,mint a){os<>(istream &is,mint &a){ long long b;is>>b;a=b; return is; } template struct GroupAdd { using value_type = X; static constexpr X op(const X &x, const X &y) noexcept { return x + y; } static constexpr void Rchop(X&x, const X&y){ x+=y; } static constexpr void Lchop(const X&x, X&y){ y+=x; } static constexpr X inverse(const X &x) noexcept { return -x; } static constexpr X power(const X &x, long long n) noexcept { return X(n) * x; } static constexpr X unit() { return X(0); } static constexpr bool commute = true; }; template> class FenwickTree{ using T=typename AbelGroup::value_type; int n; vector dat,raw; public: FenwickTree(){ assert(AbelGroup::commute); } FenwickTree(int n):n(n){ assert(AbelGroup::commute); dat=raw=vector(n,AbelGroup::unit()); } FenwickTree(const vector&v):n(v.size()),raw(v),dat(v){ assert(AbelGroup::commute); for(int i=1;i<=n;i++){ int j=i+(i&-i); if(j<=n)AbelGroup::Rchop(dat[j-1],dat[i-1]); } } T operator[](int k)const{ return raw[k]; } T get(int k)const{ return raw[k]; } void set(int k,const T&x){ T diff=AbelGroup::op(x,AbelGroup::inverse(raw[k])); raw[k]=x; for(++k;k<=n;k+=k&-k)AbelGroup::Rchop(dat[k-1],diff); } void multiply(int k,const T&x){ AbelGroup::Rchop(raw[k],x); for(++k;k<=n;k+=k&-k)AbelGroup::Rchop(dat[k-1],x); } void add(int k,const T&x){ multiply(k,x); } T prod(int k)const{ T res=AbelGroup::unit(); while(k>0){ AbelGroup::Rchop(res, dat[k-1]); k -= k&-k; } return res; } T sum(int k)const{ return prod(k); } T prod(int L,int R)const{ T pos=AbelGroup::unit(); while(L> v; INT(a);v.emplace_back(a,a); REP(n-1){ INT(b); if(v.back().second+1 == b)v.back().second++; else v.emplace_back(b,b); } FenwickTree> FT(k+1); FT.set(0,1); for(int i=1;i<=k;i++){ CFOR(l,r,v){ int L=max(0,i-r); int R=i-l+1; if(R<=0)break; FT.add(i,FT.sum(L,R)); } } cout<