#line 1 "combined.cpp" #include #include #include namespace atcoder { struct dsu { public: dsu() : _n(0) {} dsu(int n) : _n(n), parent_or_size(n, -1) {} int merge(int a, int b) { assert(0 <= a && a < _n); assert(0 <= b && b < _n); int x = leader(a), y = leader(b); if (x == y) return x; if (-parent_or_size[x] < -parent_or_size[y]) std::swap(x, y); parent_or_size[x] += parent_or_size[y]; parent_or_size[y] = x; return x; } bool same(int a, int b) { assert(0 <= a && a < _n); assert(0 <= b && b < _n); return leader(a) == leader(b); } int leader(int a) { assert(0 <= a && a < _n); if (parent_or_size[a] < 0) return a; return parent_or_size[a] = leader(parent_or_size[a]); } int size(int a) { assert(0 <= a && a < _n); return -parent_or_size[leader(a)]; } std::vector> groups() { std::vector leader_buf(_n), group_size(_n); for (int i = 0; i < _n; i++) { leader_buf[i] = leader(i); group_size[leader_buf[i]]++; } std::vector> result(_n); for (int i = 0; i < _n; i++) { result[i].reserve(group_size[i]); } for (int i = 0; i < _n; i++) { result[leader_buf[i]].push_back(i); } result.erase( std::remove_if(result.begin(), result.end(), [&](const std::vector& v) { return v.empty(); }), result.end()); return result; } private: int _n; std::vector parent_or_size; }; } // namespace atcoder #include #line 70 "combined.cpp" using namespace std; using lint = long long; void solve() { int n, m; cin >> n >> m; vector xs(n); for (auto& x : xs) cin >> x; xs.insert(xs.begin(), 0); xs.push_back(0); for (int i = 0; i <= n; i += 2) { xs[i] = -xs[i]; } vector ds(n + 1); for (int i = 0; i <= n; ++i) { ds[i] = xs[i + 1] - xs[i]; } atcoder::dsu uf(n + 1); while (m--) { int l, r; cin >> l >> r; uf.merge(--l, r); } for (auto g : uf.groups()) { lint sum = 0; for (auto v : g) sum += ds[v]; if (sum != 0) { cout << "NO\n"; return; } } cout << "YES\n"; } int main() { cin.tie(nullptr); ios::sync_with_stdio(false); solve(); return 0; }