#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000001



int main(){
	
	int n;
	cin>>n;
	
	vector<int> a(n);
	rep(i,n)cin>>a[i];
	int S = 100 * 3;
	vector dp(S,vector(S,vector<long long>(3,0)));
	rep(i,S){
		dp[i][0][0] = 1;
	}
	
	rep(i,n){
		vector ndp(S,vector(S,vector<long long>(3,0)));
		rep(j,S){
			rep(k,S){
				rep(l,3){
					if(dp[j][k][l]==0)continue;
					ndp[j][k][l] += dp[j][k][l];
					int nj = j;
					int nk = k;
					int nl = min(2,l+1);
					if(a[i] - nj > 0 )continue;
					nk += abs(a[i]-j);
					if(nk > j)continue;
					ndp[nj][nk][nl] += dp[j][k][l];
				}
			}
		}
	//	cout<<i<<endl;
		swap(dp,ndp);
	}
	

	
	long long ans = 0;
	for(int i=0;i<S;i++)ans += dp[i][i][2];
	
	
	
	cout<<ans<<endl;
		
	
	
	return 0;
}