#include using namespace std; // #define int long long #define rep(i, n) for (long long i = (long long)(0); i < (long long)(n); ++i) #define reps(i, n) for (long long i = (long long)(1); i <= (long long)(n); ++i) #define rrep(i, n) for (long long i = ((long long)(n)-1); i >= 0; i--) #define rreps(i, n) for (long long i = ((long long)(n)); i > 0; i--) #define irep(i, m, n) for (long long i = (long long)(m); i < (long long)(n); ++i) #define ireps(i, m, n) for (long long i = (long long)(m); i <= (long long)(n); ++i) #define irreps(i, m, n) for (long long i = ((long long)(n)-1); i > (long long)(m); ++i) #define SORT(v, n) sort(v, v + n); #define REVERSE(v, n) reverse(v, v+n); #define vsort(v) sort(v.begin(), v.end()); #define all(v) v.begin(), v.end() #define mp(n, m) make_pair(n, m); #define cinline(n) getline(cin,n); #define replace_all(s, b, a) replace(s.begin(),s.end(), b, a); #define PI (acos(-1)) #define FILL(v, n, x) fill(v, v + n, x); #define sz(x) (long long)(x.size()) using ll = long long; using vi = vector; using vvi = vector; using vll = vector; using vvll = vector; using pii = pair; using pll = pair; using vs = vector; using vpll = vector>; using vtp = vector>; using vb = vector; template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } template using vc=vector; template using vvc=vc>; const ll INF = 1e9+10; const ll MOD = 1e9+7; const ll LINF = 1e18; signed main() { cin.tie( 0 ); ios::sync_with_stdio( false ); ll n; cin>>n; ll sum=0; vll a(n-1); rep(i,n-1) { cin>>a[i]; sum+=a[i]; } // 総和を見れば良さそう // 木を作れるかという問題 // n-1辺で全てを網羅 // a[i]が1つ存在すれば、a[i]+1のノードへは到達可能 // b[i]をa[i]で埋めて、埋まってないところは直近の右からの距離になる // a[i]+1==iなるiを埋める // それで埋まらなかったiは、小さい値から使っていく ll ma=n*(n-1)/2, mi=n-1; // cout<