#pragma comment(linker, "/STACK:1024000000,1024000000")#include<cstdio>#include<cstring>#include<cmath>#include<algorithm>#include<vector>#include<map>#include<set>#include<queue>#include<stack>#include<iostream>using namespace std;typedef long long LL;const double pi=acos(-1.0),eps=1e-6;void File(){    freopen("D:\\in.txt","r",stdin);    freopen("D:\\out.txt","w",stdout);}template <class T>inline void read(T &x){    char c=getchar(); x=0;    while(!isdigit(c)) c=getchar();    while(isdigit(c)) {x=x*10+c-‘0‘; c=getchar();}}const int maxn=100010;int a[maxn],n,tmp,dp[maxn][30];LL ans[maxn];void RMQ_init(){    for(int i=0;i<n;i++) dp[i][0]=i;    for(int j=1;(1<<j)<=n;j++)        for(int i=0;i+(1<<j)-1<n;i++){            if(a[dp[i][j-1]]>a[dp[i+(1<<(j-1))][j-1]]) dp[i][j]=dp[i][j-1];            else dp[i][j]=dp[i+(1<<(j-1))][j-1];        }}int RMQ(int L,int R){    int k=0;    while((1<<(k+1))<=R-L+1) k++;    if(a[dp[L][k]]>a[dp[R-(1<<k)+1][k]]) return dp[L][k];    return dp[R-(1<<k)+1][k];}int main(){    scanf("%d",&n);    for(int i=0;i<n-1;i++) scanf("%d",&a[i]),a[i]--;    a[n-1]=n-1; RMQ_init(); ans[n-1]=0; LL d=0;    for(int i=n-2;i>=0;i--)    {        tmp=RMQ(i+1,a[i]);        ans[i]=ans[tmp]-(a[i]-tmp)+n-1-a[i]+a[i]-i;        d=d+ans[i];    }    printf("%lld\n",d);    return 0;}

#pragma comment(linker, "/STACK:1024000000,1024000000")#include<cstdio>#include<cstring>#include<cmath>#include<algorithm>#include<vector>#include<map>#include<set>#include<queue>#include<stack>#include<iostream>using namespace std;typedef long long LL;const double pi=acos(-1.0),eps=1e-6;void File(){    freopen("D:\\in.txt","r",stdin);    freopen("D:\\out.txt","w",stdout);}template <class T>inline void read(T &x){    char c=getchar(); x=0;    while(!isdigit(c)) c=getchar();    while(isdigit(c)) {x=x*10+c-‘0‘; c=getchar();}}const int maxn=100010;int a[maxn],n,s[4*maxn],M,tmp;LL ans[maxn];void build(int l,int r,int rt){    if(l==r) { s[rt]=a[l]; return; }    int m=(l+r)/2; build(l,m,2*rt); build(m+1,r,2*rt+1);    s[rt]=max(s[2*rt],s[2*rt+1]);}void f(int L,int R,int l,int r,int rt){    if(L<=l&&r<=R) { M=max(M,s[rt]); return; }    int m=(l+r)/2;    if(L<=m) f(L,R,l,m,2*rt);    if(R>m) f(L,R,m+1,r,2*rt+1);}void force(int l,int r,int rt){    if(l==r) {tmp=l; return;}    int m=(l+r)/2;    if(s[2*rt]==M) force(l,m,2*rt);    else force(m+1,r,2*rt+1);}void h(int L,int R,int l,int r,int rt){    if(L<=l&&r<=R)    {        if(s[rt]<M) return;        force(l,r,rt); return;    }    int m=(l+r)/2;    if(L<=m) h(L,R,l,m,2*rt); if(tmp!=-1) return;    if(R>m) h(L,R,m+1,r,2*rt+1); if(tmp!=-1) return;}int main(){    scanf("%d",&n);    for(int i=1;i<=n-1;i++) scanf("%d",&a[i]); a[n]=n;    build(1,n,1); ans[n]=0; LL d=0;    for(int i=n-1;i>=1;i--)    {        M=tmp=-1; f(i+1,a[i],1,n,1); h(i+1,a[i],1,n,1);        ans[i]=ans[tmp]-(a[i]-tmp)+n-a[i]+a[i]-i;        d=d+ans[i];    }    printf("%lld\n",d);    return 0;}