import sys
def I(): return int(sys.stdin.readline().rstrip())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))


N = I()
A = [0]+LI()
mod = 998244353

dp = [[{} for _ in range(N+1)] for _ in range(N)]
dp[N-1][N][A[N]-A[N-1]] = 1
for i in range(N-1,1,-1):
    for j in range(i+1,N+1):
        for k in dp[i][j].keys():
            a = dp[i][j][k]
            m0 = max(k,A[i]-A[i-1])
            m1 = max(k,A[j]-A[i-1])
            if m0 in dp[i-1][j].keys():
                dp[i-1][j][m0] += a
                dp[i-1][j][m0] %= mod
            else:
                dp[i-1][j][m0] = a
            if m1 in dp[i-1][i].keys():
                dp[i-1][i][m1] += a
                dp[i-1][i][m1] %= mod
            else:
                dp[i-1][i][m1] = a

ans = 0
for j in range(2,N+1):
    for k in dp[1][j].keys():
        ans += dp[1][j][k]*k
        ans %= mod

print((2*ans) % mod)