#include <bits/stdc++.h>using namespace std;#define maxn 100009const int MOD = 1e9 + 7;int main(){    int n;    int a[maxn];    int dp[maxn];    int cnt[11];        while (~scanf("%d",&n))    {        memset(a,0,sizeof(a));        memset(dp,0,sizeof(dp));        for (int i = 1;i<=n;i++)        {            scanf("%d",&a[i]);        }        dp[0] = 1;        for (int i = 1;i<=n;i++)        {            memset(cnt,0,sizeof(cnt));            for (int j = 0;j<i;j++)            {                cnt[a[i-j]]++;                if (cnt[a[i-j]] > 1)                {                    break;                }                dp[i] = (dp[i] + dp[i-j-1])%MOD;            }        }        printf("%d\n",dp[n]);    }    return 0;}