#include <bits/stdc++.h>
#define pb emplace_back
#define fst first
#define scd second
#define mkp make_pair
#define mems(a, x) memset((a), (x), sizeof(a))

using namespace std;
typedef long long ll;
typedef double db;
typedef unsigned long long ull;
typedef long double ldb;
typedef pair<ll, ll> pii;

const int maxn = 1000100;
const ll mod = 1000000007, P = 998244353123456789;

ll n, a[maxn], f[maxn], pw[maxn];

void cdq(int l, int r) {
	if (l == r) {
		f[l] = (f[l] + f[l - 1]) % mod;
		return;
	}
	int mid = (l + r) >> 1;
	cdq(l, mid);
	map<ll, ll> mp, pm;
	ll x = 0;
	for (int i = mid; i >= l; --i) {
		x = (x + pw[a[i]]) % P;
		mp[x] = (mp[x] + f[i - 1]) % mod;
	}
	x = 0;
	for (int i = mid + 1; i <= r; ++i) {
		x = (x + pw[a[i]]) % P;
		ll t = a[i];
		++pm[t];
		while (pm[t] >= 2) {
			++pm[t + 1];
			pm[t++] -= 2;
		}
		ll y = (--pm.end())->fst;
		f[i] = (f[i] + mp[(pw[y + 1] - x + P) % P]) % mod;
	}
	mp.clear();
	pm.clear();
	x = 0;
	for (int i = mid; i >= l; --i) {
		x = (x + pw[a[i]]) % P;
		ll t = a[i];
		++pm[t];
		while (pm[t] >= 2) {
			++pm[t + 1];
			pm[t++] -= 2;
		}
		ll y = (--pm.end())->fst;
		if (x != pw[y]) {
			mp[(pw[y + 1] - x + P) % P] = (mp[(pw[y + 1] - x + P) % P] + f[i - 1]) % mod;
		}
	}
	x = 0;
	for (int i = mid + 1; i <= r; ++i) {
		x = (x + pw[a[i]]) % P;
		f[i] = (f[i] + mp[x]) % mod;
	}
	cdq(mid + 1, r);
}

void solve() {
	scanf("%lld", &n);
	pw[0] = 1;
	for (int i = 1; i < maxn; ++i) {
		pw[i] = pw[i - 1] * 2 % P;
	}
	for (int i = 1; i <= n; ++i) {
		scanf("%lld", &a[i]);
	}
	f[0] = 1;
	cdq(1, n);
	printf("%lld\n", f[n]);
}

int main() {
	int T = 1;
	// scanf("%d", &T);
	while (T--) {
		solve();
	}
	return 0;
}