#include using namespace std; #define ll long long #define rep(i,n) for(int i=0;i=0;i--) #define rrep2(i,n,k) for(int i=n-1;i>=n-k;i--) #define vll(n,i) vector(n,i) #define v2ll(n,m,i) vector>(n,vll(m,i)) #define v3ll(n,m,k,i) vector>>(n,v2ll(m,k,i)) #define v4ll(n,m,k,l,i) vector>>>(n,v3ll(m,k,l,i)) #define all(v) v.begin(),v.end() #define chmin(k,m) k = min(k,m) #define chmax(k,m) k = max(k,m) #define Pr pair #define Tp tuple #define riano_ std::ios::sync_with_stdio(false);std::cin.tie(nullptr) #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math") //Graph struct graph { long long N; vector>> G; vector par_v; vector par_e; int edge_count = 0; graph(long long n) { N = n; G = vector>>(N); par_v = vector(N,-1); par_e = vector(N,-1); } void unite(long long a,long long b,long long cost = 1,bool directed = false){ G[a].emplace_back(b,cost,edge_count); if(!directed) G[b].emplace_back(a,cost,edge_count); edge_count++; } }; //map add template void add(map &cnt,T a,ll n = 1){ if(cnt.count(a)) cnt[a] += n; else cnt[a] = n; } const ll mod = 998244353; template struct modint{ uint64_t val; constexpr modint(const int64_t val_=0) noexcept:val((val_%int64_t(mod)+int64_t(mod))%int64_t(mod)){} constexpr modint operator-() const noexcept{ return modint(*this)=mod-val; } constexpr modint operator+(const modint rhs) const noexcept{ return modint(*this)+=rhs; } constexpr modint operator-(const modint rhs) const noexcept{ return modint(*this)-=rhs; } constexpr modint operator*(const modint rhs) const noexcept{ return modint(*this)*=rhs; } constexpr modint operator/(const modint rhs) const noexcept{ return modint(*this)/=rhs; } constexpr modint &operator+=(const modint rhs) noexcept{ val+=rhs.val; val-=((val>=mod)?mod:0); return (*this); } constexpr modint &operator-=(const modint rhs) noexcept{ val+=((val>=1; } return (*this)*=now; } modint & operator++(){ val++; if (val == mod) val = 0; return *this; } modint operator++(int){ modint res = *this; ++*this; return res; } constexpr bool operator==(const modint rhs) noexcept{ return val==rhs.val; } constexpr bool operator!=(const modint rhs) noexcept{ return val!=rhs.val; } friend constexpr ostream &operator<<(ostream& os,const modint x) noexcept{ return os<<(x.val); } friend constexpr istream &operator>>(istream& is,modint& x) noexcept{ uint64_t t; is>>t,x=t; return is; } }; typedef modint mint; mint pw(long long a,long long b,long long m = mod){ if(a%m==0) return mint(0); if(b==0) return mint(1); else if(b%2==0){ long long x = pw(a,b/2,m).val; return mint(x*x); } else{ long long x = pw(a,b-1,m).val; return mint(a*x); } } mint modinv(long long a, long long m = mod) { long long b = m, u = 1, v = 0; while (b) { long long t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } u %= m; return mint(u); } #define vm(n,i) vector(n,i) #define v2m(n,m,i) vector>(n,vm(m,i)) #define v3m(n,m,k,i) vector>>(n,v2m(m,k,i)) #define v4m(n,m,k,l,i) vector>>>(n,v3m(m,k,l,i)) void out(vector &v){ for(ll x:v) cout << x << " "; cout << "\n"; return; } //convolution template< int mod > struct ModInt { int x; ModInt() : x(0) {} ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} ModInt &operator+=(const ModInt &p) { if((x += p.x) >= mod) x -= mod; return *this; } ModInt &operator-=(const ModInt &p) { if((x += mod - p.x) >= mod) x -= mod; return *this; } ModInt &operator*=(const ModInt &p) { x = (int) (1LL * x * p.x % mod); return *this; } ModInt &operator/=(const ModInt &p) { *this *= p.inverse(); return *this; } ModInt operator-() const { return ModInt(-x); } ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; } ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; } ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; } ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; } bool operator==(const ModInt &p) const { return x == p.x; } bool operator!=(const ModInt &p) const { return x != p.x; } ModInt inverse() const { int a = x, b = mod, u = 1, v = 0, t; while(b > 0) { t = a / b; swap(a -= t * b, b); swap(u -= t * v, v); } return ModInt(u); } ModInt pow(int64_t n) const { ModInt ret(1), mul(x); while(n > 0) { if(n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; } friend istream &operator>>(istream &is, ModInt &a) { int64_t t; is >> t; a = ModInt< mod >(t); return (is); } static int get_mod() { return mod; } }; using mint_ = ModInt< mod >; namespace FastFourierTransform { using real = double; struct C { real x, y; C() : x(0), y(0) {} C(real x, real y) : x(x), y(y) {} inline C operator+(const C &c) const { return C(x + c.x, y + c.y); } inline C operator-(const C &c) const { return C(x - c.x, y - c.y); } inline C operator*(const C &c) const { return C(x * c.x - y * c.y, x * c.y + y * c.x); } inline C conj() const { return C(x, -y); } }; const real PI = acosl(-1); int base = 1; vector< C > rts = { {0, 0}, {1, 0} }; vector< int > rev = {0, 1}; void ensure_base(int nbase) { if(nbase <= base) return; rev.resize(1 << nbase); rts.resize(1 << nbase); for(int i = 0; i < (1 << nbase); i++) { rev[i] = (rev[i >> 1] >> 1) + ((i & 1) << (nbase - 1)); } while(base < nbase) { real angle = PI * 2.0 / (1 << (base + 1)); for(int i = 1 << (base - 1); i < (1 << base); i++) { rts[i << 1] = rts[i]; real angle_i = angle * (2 * i + 1 - (1 << base)); rts[(i << 1) + 1] = C(cos(angle_i), sin(angle_i)); } ++base; } } void fft(vector< C > &a, int n) { assert((n & (n - 1)) == 0); int zeros = __builtin_ctz(n); ensure_base(zeros); int shift = base - zeros; for(int i = 0; i < n; i++) { if(i < (rev[i] >> shift)) { swap(a[i], a[rev[i] >> shift]); } } for(int k = 1; k < n; k <<= 1) { for(int i = 0; i < n; i += 2 * k) { for(int j = 0; j < k; j++) { C z = a[i + j + k] * rts[j + k]; a[i + j + k] = a[i + j] - z; a[i + j] = a[i + j] + z; } } } } vector< int64_t > multiply(const vector< int > &a, const vector< int > &b) { int need = (int) a.size() + (int) b.size() - 1; int nbase = 1; while((1 << nbase) < need) nbase++; ensure_base(nbase); int sz = 1 << nbase; vector< C > fa(sz); for(int i = 0; i < sz; i++) { int x = (i < (int) a.size() ? a[i] : 0); int y = (i < (int) b.size() ? b[i] : 0); fa[i] = C(x, y); } fft(fa, sz); C r(0, -0.25 / (sz >> 1)), s(0, 1), t(0.5, 0); for(int i = 0; i <= (sz >> 1); i++) { int j = (sz - i) & (sz - 1); C z = (fa[j] * fa[j] - (fa[i] * fa[i]).conj()) * r; fa[j] = (fa[i] * fa[i] - (fa[j] * fa[j]).conj()) * r; fa[i] = z; } for(int i = 0; i < (sz >> 1); i++) { C A0 = (fa[i] + fa[i + (sz >> 1)]) * t; C A1 = (fa[i] - fa[i + (sz >> 1)]) * t * rts[(sz >> 1) + i]; fa[i] = A0 + A1 * s; } fft(fa, sz >> 1); vector< int64_t > ret(need); for(int i = 0; i < need; i++) { ret[i] = llround(i & 1 ? fa[i >> 1].y : fa[i >> 1].x); } return ret; } }; template< typename T > struct ArbitraryModConvolution { using real = FastFourierTransform::real; using C = FastFourierTransform::C; ArbitraryModConvolution() = default; vector< T > multiply(const vector< T > &a, const vector< T > &b, int need = -1) { if(need == -1) need = a.size() + b.size() - 1; int nbase = 0; while((1 << nbase) < need) nbase++; FastFourierTransform::ensure_base(nbase); int sz = 1 << nbase; vector< C > fa(sz); for(int i = 0; i < a.size(); i++) { fa[i] = C(a[i].x & ((1 << 15) - 1), a[i].x >> 15); } fft(fa, sz); vector< C > fb(sz); if(a == b) { fb = fa; } else { for(int i = 0; i < b.size(); i++) { fb[i] = C(b[i].x & ((1 << 15) - 1), b[i].x >> 15); } fft(fb, sz); } real ratio = 0.25 / sz; C r2(0, -1), r3(ratio, 0), r4(0, -ratio), r5(0, 1); for(int i = 0; i <= (sz >> 1); i++) { int j = (sz - i) & (sz - 1); C a1 = (fa[i] + fa[j].conj()); C a2 = (fa[i] - fa[j].conj()) * r2; C b1 = (fb[i] + fb[j].conj()) * r3; C b2 = (fb[i] - fb[j].conj()) * r4; if(i != j) { C c1 = (fa[j] + fa[i].conj()); C c2 = (fa[j] - fa[i].conj()) * r2; C d1 = (fb[j] + fb[i].conj()) * r3; C d2 = (fb[j] - fb[i].conj()) * r4; fa[i] = c1 * d1 + c2 * d2 * r5; fb[i] = c1 * d2 + c2 * d1; } fa[j] = a1 * b1 + a2 * b2 * r5; fb[j] = a1 * b2 + a2 * b1; } fft(fa, sz); fft(fb, sz); vector< T > ret(need); for(int i = 0; i < need; i++) { int64_t aa = llround(fa[i].x); int64_t bb = llround(fb[i].x); int64_t cc = llround(fa[i].y); aa = T(aa).x, bb = T(bb).x, cc = T(cc).x; ret[i] = aa + (bb << 15) + (cc << 30); } return ret; } }; int main(){ riano_; string ans = "Yes"; ll N,M,K,H,W,Q,L,R,T; cin >> N; vector b(N+2,0); rep(i,N) cin >> b[i+1]; vector op(N+1,0); stack s; ll last = -1; s.push(-1); vector req(N+2,0); rep(i,N+1){ if((b[i]+b[i+1])%2==1){ if(last!=-1&&(i+1+last)%2==0){ s.pop(); last = s.top(); req[i+1]--; } else{ last = i+1; s.push(last); req[i+1]++; } } } rep(i,N+1){ req[i+1] += req[i]; } rep(i,N+2){ b[i] -= req[i]; } rep(i,N){ op[i+1] = b[i+1] - op[i]; if(op[i+1]<0) ans = "No"; } if(op[N]!=0) ans = "No"; cout << ans << endl; }