n = int(input())
a = list(map(int,input().split()))
s = set(a); m = max(a); ans = 0
for k in range(1,m):
    for t in range(1,m):
        p = [t,t+k+10,t+10,t+k+11]; f = True
        for v in p: f &= v in s
        if not f: continue
        dp = [1,0,0,0,0]
        for v in a:
            if v in p: i = p.index(v); dp[i+1] += dp[i]
        ans += dp[4]
print(ans)