#pragma region header #ifdef LOCAL_ENV #include #else #include #include #include #include #include #define dump(...) #define CPP_DUMP_SET_OPTION(...) #define CPP_DUMP_SET_OPTION_GLOBAL(...) #define CPP_DUMP_DEFINE_EXPORT_OBJECT(...) #define CPP_DUMP_DEFINE_EXPORT_ENUM(...) #define CPP_DUMP_DEFINE_EXPORT_OBJECT_GENERIC(...) #endif using namespace std; using namespace atcoder; using namespace __gnu_pbds; #define ALL(a) (a).begin(), (a).end() #define RALL(a) (a).rbegin(), (a).rend() #define FOR(i, start, end) for (int i = start; i < (int)(end); ++i) #define RFOR(i, rstart, rend) for (int i = rstart; i >= (int)(rend); --i) #define REP(i, end) FOR(i, 0, end) #define BIT(x, i) (((x)>>(i))&1) using ll = long long; using ull = unsigned long long; using pii = pair; using pll = pair; using pli = pair; template void read(T& val) {cin >> val;} template void read(T& val, Args&... args) {cin >> val;read(args...);} #define DEF(type, ...) type __VA_ARGS__;read(__VA_ARGS__) constexpr ll LINF = 1LL << 60; constexpr int INF = 1 << 30; template using TREE = tree, rb_tree_tag, tree_order_statistics_node_update>; template using Graph = vector>; template using PQ = priority_queue, greater>; void yes(bool expr) {cout << (expr ? "Yes" : "No") << "\n";} template bool chmax(T &a, const T &b) { if (a bool chmin(T &a, const T &b) { if (b istream &operator>>(istream&is,vector&v){for(T &in:v){is>>in;}return is;} template ostream &operator<<(ostream&os,const vector&v){for(auto it=v.begin();it!=v.end();){os<<*it<<((++it)!=v.end()?" ":"\n");}return os;} // 区間をsetで管理する template struct RangeSet{ set> st; T TINF; RangeSet(){ TINF = numeric_limits::max()/2; st.emplace(-TINF,-TINF); st.emplace(TINF,TINF); } RangeSet(T tinf):TINF(tinf){ st.emplace(-TINF,-TINF); st.emplace(TINF,TINF); } // [l,r) covered? bool covered(T l, T r){ auto it = prev(st.lower_bound({l+1,l+1})); return it->first <= l && r <= it->second; } bool covered(T x){ return covered(x,x+1); } // [l, r)がカバーされているなら,その区間を返す. されていないなら{TINF,TINF}を返す pair get_covered(T l, T r){ auto it = prev(st.lower_bound({l+1,l+1})); if(it->first <= l && r <= it->second) return *it; return {TINF,TINF}; } pair get_covered(T x){ return get_covered(x,x+1); } // insert[l,r), 増加量を返す T insert(T l, T r){ auto it = prev(st.lower_bound({l+1,l+1})); T ret = 0; if(it->first <= l && r <= it->second) return 0; if(it->first <= l && l <= it->second){ l = it->first; ret -= it->second - it->first; it = st.erase(it); }else { it = next(it); } while(it->first <= r){ ret -= it->second - it->first; r = max(r,it->second); it = st.erase(it); } st.emplace(l,r); ret += r - l; return ret; } T insert(T x){ return insert(x,x+1); } // erase[l,r), 減少量を返す T erase(T l, T r){ auto it = prev(st.lower_bound({l+1,l+1})); T ret = 0; if(it->first <= l && r <= it->second){ ret += r - l; if(it->first < l) st.emplace(it->first,l); if(r < it->second) st.emplace(r,it->second); st.erase(it); return ret; } if(it->first <= l && l < it->second){ ret += it->second - l; if(it->first < l) st.emplace(it->first,l); it = st.erase(it); }else { it = next(it); } while(it->first < r){ ret += it->second - it->first; if(r < it->second) { ret -= it->second - r; st.emplace(r,it->second); } it = st.erase(it); } return ret; } T erase(T x){ return erase(x,x+1); } // number of ranges int size(){ return st.size()-2; } T mex(T x = 0){ auto it = prev(st.lower_bound({x+1,x+1})); if(it->first <= x && x < it->second ) return it->second; return x; } void output(){ cout<<"RangeSet : "; for(auto &p:st){ if(p.first==-TINF || p.second==TINF) continue; cout<<"["< struct Binomial{ std::vector fact_vec, fact_inv_vec; void extend(int m = -1){ int n = fact_vec.size(); if (m == -1) m = n * 2; if (n >= m) return; fact_vec.resize(m); fact_inv_vec.resize(m); for (int i = n; i < m; i++){ fact_vec[i] = fact_vec[i - 1] * T(i); } fact_inv_vec[m - 1] = T(1) / fact_vec[m - 1]; for (int i = m - 1; i > n; i--){ fact_inv_vec[i - 1] = fact_inv_vec[i] * T(i); } } Binomial(int MAX = 2){ fact_vec.resize(1, T(1)); fact_inv_vec.resize(1, T(1)); extend(MAX + 1); } T fact(int i){ if (i < 0) return 0; while (int(fact_vec.size()) <= i) extend(); return fact_vec[i]; } T invfact(int i){ if (i < 0) return 0; while (int(fact_inv_vec.size()) <= i) extend(); return fact_inv_vec[i]; } T C(int a, int b){ if (a < b || b < 0) return 0; return fact(a) * invfact(b) * invfact(a - b); } T invC(int a, int b){ if (a < b || b < 0) return 0; return fact(b) * fact(a - b) *invfact(a); } T P(int a, int b){ if (a < b || b < 0) return 0; return fact(a) * invfact(a - b); } T inv(int a){ if (a < 0) return inv(-a) * T(-1); if (a == 0) return 1; return fact(a - 1) * invfact(a); } }; // 有向グラフをDAGに変換する Graph toDAG(const Graph &G){ int n = G.size(); scc_graph scc(n); REP(i,n) for(auto &to:G[i]) scc.add_edge(i,to); auto sccs = scc.scc(); int m = sccs.size(); vector id(n); REP(i,m) for(auto &v:sccs[i]) id[v] = i; Graph ret(m); REP(i,n) for(auto &to:G[i]) if(id[i]!=id[to]) ret[id[i]].push_back(id[to]); REP(i,m) sort(ALL(ret[i])), ret[i].erase(unique(ALL(ret[i])),ret[i].end()); return ret; } /* 文字列、数列が一様か判定 */ template struct UniformSegmentChecker { const T &v; const int n; vector diff; UniformSegmentChecker(const T &v) : v(v), n(v.size()), diff(v.size(),0) { REP(i,n-1){ diff[i+1] = diff[i] + (v[i] != v[i+1]);} } bool is_uniform(int l, int r) const { assert(0 <= l && l < r && r <= n); return diff[l] == diff[r-1]; } }; /* 回文判定 */ bool isPalindrome(const string &s){int sz=s.size(); REP(i,sz/2){if(s[i]!=s[sz-1-i])return false;} return true;} /* 座標圧縮 */ template vector compress(const vector&A){vector ret(A.size()); auto tmp = A; sort(ALL(tmp)); tmp.erase(unique(ALL(tmp)), tmp.end()); REP(i,A.size()) ret[i] = lower_bound(ALL(tmp), A[i]) - tmp.begin(); return ret;} /* 約数列挙 整数nの約数のvectorを返す */ vector enumdiv(ll n){vectors; for(ll i = 1;i*i<=n;i++){if(n%i==0){s.push_back(i);if(i*i!=n)s.push_back(n/i);}}return s;} /* 素因数分解 pair<素数、指数>のvectorを返す */ vector primeDecomposition(ll x){vector ret;int i=2,sq=99,d=2;while(i<=sq){int k=0;while(x%i==0){x/=i;++k;}if(k>0){ret.emplace_back(i,k);}if(k>0 || i==97) {sq = sqrt(x)+0.5;}if(i<4){i = (i<<1)-1;}else{i += d;d ^= 6;}}if(x>1) ret.emplace_back(x,1);return ret;} /* エラトステネスの篩 n未満の素数を列挙。isprimeには素数かどうかが入っている */ vector isprime;vector era(int n) {isprime.resize(n, true);vector res;isprime[0] = false; isprime[1] = false;for (int i = 2; i < n; ++i){if (isprime[i]) {res.push_back(i);for (int j = i*2; j < n; j += i) isprime[j] = false;}}return res;} /* トポロジカルソート */ vector topo_sort(const Graph &G){int n = G.size();vector deg(n), ret;for(const auto &v:G)for(const auto &to:v) ++deg[to];queue que;REP(i,n) if(deg[i]==0)que.push(i);while(!que.empty()){const int from = que.front();que.pop();ret.push_back(from);for(const auto &to:G[from])if(--deg[to]==0) que.push(to);}return ret;}; /* 拡張ユークリッドの互除法 [gcd,x,y] ax+by=gcd(a,b) */ tuple ex_gcd(ll a, ll b){if(b==0) return {a,1,0}; auto [g,x,y] = ex_gcd(b, a%b); return {g,y,x-a/b*y};} /* 辞書順で次の分割数を求める */ template bool next_partition(vector &a){const int n = a.size(); if(n<=1) {return false;} T sum=a[n-1]; a.pop_back(); while(true){T x = a.back(); a.pop_back(); sum += x; if(a.empty() || a.back() > x){a.push_back(x+1); a.resize(a.size()+sum-x-1, 1); break;}} return true;} /* iを中心として回文となる半径を全て求める O(n) */ template vector manachar(const T &s) {int n = s.size();vectorr(n);int i=0,j=0;while(i=0&&i+j=0); } using mint = modint998244353; //using mint = modint1000000007; //using mint = modint; istream &operator>>(istream&is,mint&p){ll x;cin >> x;p=x; return is;} ostream &operator<<(ostream&os,const mint&p){os << p.val();return os;} #pragma endregion header int main() { ios::sync_with_stdio(false); cin.tie(0); cout.tie(0); int n; cin >> n; vector H(n); cin >> H; deque dq; int ans = 0; dq.push_back({INF, 1}); REP(i,n){ int cur = i%2; int last = 0; while(dq.front().first <= H[i]){ auto [h, col] = dq.front(); dq.pop_front(); if(col==cur) { last = h; continue; } if(cur==1){ ans -= h-last; }else{ ans += h-last; } last = h; } auto [h, col] = dq.front(); if(cur!=col){ if(cur==0){ ans += H[i]-last; }else{ ans -= H[i]-last; } dq.push_front({H[i], cur}); } assert(ans >= 0); cout << ans << endl; } return 0; }