#include #include #define rep(i,b) for(int i=0;i=0;i--) #define rep1(i,b) for(int i=1;i using mpq = priority_queue, greater>; template bool chmax(T &a, const T &b) { if (a bool chmin(T &a, const T &b) { if (b ll sumv(const vector&a){ll res(0);for(auto&&x:a)res+=x;return res;} bool yn(bool a) { if(a) {cout << "Yes" << endl; return 1;} else {cout << "No" << endl; return 0;}} #define dame { cout << "No" << endl; return 0;} #define dame1 { cout << -1 << endl; return 0;} #define test(x) cout << "test" << x << endl; #define deb(x,y) cout << x << " " << y << endl; #define deb3(x,y,z) cout << x << " " << y << " " << z << endl; #define deb4(x,y,z,x2) cout << x << " " << y << " " << z << " " << x2 << endl; #define out cout << ans << endl; #define outv fore(yans , ans) cout << yans << "\n"; #define show(x) cerr<<#x<<" = "<; using pil = pair; using pli = pair; using pii = pair; using tp = tuple; using vi = vector; using vl = vector; using vs = vector; using vb = vector; using vpii = vector; using vpli = vector; using vpll = vector; using vpil = vector; using vvi = vector>; using vvl = vector>; using vvs = vector>; using vvb = vector>; using vvpii = vector>; using vvpli = vector>; using vvpll = vector; using vvpil = vector; using mint = modint998244353; using vm = vector; using vvm = vector>; vector dx={1,0,-1,0,1,1,-1,-1},dy={0,1,0,-1,1,-1,1,-1}; ll gcd(ll a, ll b) { return a?gcd(b%a,a):b;} ll lcm(ll a, ll b) { return a/gcd(a,b)*b;} const double eps = 1e-10; const ll LINF = 1001002003004005006ll; const int INF = 1001001001; int main(){ int n; cin>>n; bool ok = true; vi c(n); int pre = 0; rep(i,n){ ll tmp; cin>>tmp; c[i] = tmp - pre; if (c[i] < 0) ok = false; pre = c[i]; } int cnt = 0; bool one = false; bool con = false; if (c[0]%2 == 0 && c[0] >= 2) con = true; rep(i,n){ if (one){ if (c[i]%2 == 1) cnt++; else{ one = false; if (cnt%2 == 0){ if (c[i] >= 2) {cnt = 1; con = true;} else if(!con) ok = false; continue; } cnt = 0; } }else{ if (c[i]%2 == 1) {one = true; cnt++;} else{ if (con){ if (c[i] == 0) {cnt = 0; con = false;} else cnt++; } } } } if (one && cnt%2 == 0) ok = false; yn(ok); return 0; }