#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <set>
#include <stack>
#include <limits.h>
#include <math.h>
#include <iomanip>
#include <bitset>
#include <unordered_map>
#include <unordered_set>
#include <map>
#include <cstring>
#include <sstream>
#pragma GCC target("popcnt")
typedef long long ll;
typedef long double ld;
using namespace std;
const int MOD=1e6+7;
typedef pair<ll,ll>point;
//#define x first
//#define y second
int n;
int arr[10000];
int res=0;
void get(int i,int teams,bool bigger=false){
if(i==n){
if(!bigger)
res++;
return;
}
//ll res=0;
for(int new_team=0;new_team<=teams;new_team++){
//res+=get(i+1,teams,bigger||new_team>arr[i]);
get(i+1,teams,bigger||new_team>arr[i]);
}
//res+=get(i+1,teams+1,teams+1>arr[i]);
get(i+1,teams+1,bigger||teams+1>arr[i]);
//return res;
}
int main(){
ios::sync_with_stdio(false);
cout.tie(NULL);
cin.tie(NULL);
cin>>n;
for(int i=0;i<n;i++){
cin>>arr[i];
arr[i]--;
}
//cout<<get(0,0,false)<<"\n";
get(0,0,false);
cout<<res%MOD<<"\n";
return 0;
}
