#include<iostream>
#include<cstdio>
#include<algorithm>
#include<set>
#include<cstring>
#include<map>
#define boo(i) bitset<i>
#define ri register int
#define rll register long long
#define ll long long
#define mem(x) memset(x,0,sizeof(x))
#define max_(i,j) (i<j?j:i)
#define min_(i,j) (i<j?i:j)
#define abs_(x) (x>0?x:(-x))
using namespace std;
const int MAXN=2e6+5;
ll pw[MAXN];
const int mod=1e9+7;
const int hmod=1e12+7;
ll dp[MAXN];
int b[MAXN];
void solv(int l,int r){
	int mid=(l+r)>>1;
	if(l==r){
		(dp[r]+=dp[r-1])%=mod;
		return;
	}
	solv(l,mid);
	map<int,int>mp[2];
	ll pr=0;
	mp[0][0]=mid;
	for(int i=mid;i>=l;i--){
		(pr+=pw[b[i]])%=hmod;
		mp[0][pr]=i-1;
	}
	pr=0;
	set<int>s;
	int wei=0;
	for(int i=mid+1;i<=r;i++){
		(pr+=pw[b[i]])%=hmod;
		mp[1][pr]=i;
		int now=b[i];
		while(s.count(now)){
			s.erase(now);
			now++;
		}
		wei=max(wei,now);
		s.insert(now);
		if(s.size()==1){
			continue;
		}
		ll val=(pw[wei+1]-pr+hmod)%hmod;
		if(mp[0].count(val)){
			(dp[i]+=dp[mp[0][val]])%=mod;
		}
	}
	wei=pr=0;
	s.clear();
	for(int i=mid;i>=l;i--){
		(pr+=pw[b[i]])%=hmod;
		int now=b[i] ;
		while(s.count(now)){
			s.erase(now);
			now++;
		}
		wei=max(wei,now);
		s.insert(now);
		ll val=(pw[wei+1]-pr+hmod)%hmod;
		if(mp[1].count(val)){
			(dp[mp[1][val]]+=dp[i-1])%=mod;
		}
	}
	solv(mid+1,r);
}
int main(){
	int n;
	scanf("%d",&n);pw[0]=1;
	for(int i=1;i<=1.5e6;i++){
		pw[i]=pw[i-1]*2%hmod;
	}
	dp[0]=1;
	for(int i=1;i<=n;i++){
		scanf("%d",&b[i]);
	}
	solv(1,n);
	printf("%lld",dp[n]);
}