import java.util.*;
public class Main {
public static void main (String args[]) {
Scanner sc=new Scanner(System.in);
int n=sc.nextInt();
int[]arr = new int[n];
for(int i=0;i<n;i++){
arr[i]=sc.nextInt();
}
if(checkCircular(arr)){
System.out.print(“1”);
}else{
System.out.print(“0”);
}
}
static int nextIndex(int[]arr,int i){
return ((i+arr[i]+arr.length)%arr.length);
}
static Boolean checkCircular(int[]arr){
for(int i=0;i<arr.length;i++){
if(arr[i]==0){
continue;
}
int fast=i,slow=i;
while(slownextIndex(arr,slow)>0&&
fastnextIndex(arr,fast)>0&&
fastnextIndex(arr,nextIndex(arr,fast))>0){
slow=nextIndex(arr,slow);
fast=nextIndex(arr,nextIndex(arr,fast));
if(slow==fast){
if(slow==nextIndex(arr,slow)){
break;
}
return true;
}
}
slow=i;
int val=arr[slow];
while(valarr[slow]>0){
int x=slow;
slow=nextIndex(arr,slow);
arr[x]=0;
}
}
return false;
}
}
