n = int(input())
length = [0]
for i in range(n):
    length.append(int(input()))
length.sort()
vis = [1 for i in range(n+1)]
ans = [0 for i in range(4+1)]
sum = 0
def dfs(num):
    global sum
    if num > 4:
        tem = [length[ans[i+1]] for i in range(4)]
        if tem[2] == tem[3]:
            if (tem[0] + tem[1])==tem[2]:
                sum += 1
    else:
        for i in range(ans[num-1]+1, n-2):
            if vis[i]:
                vis[i] = 0
                ans[num] = i
                dfs(num+1)
                vis[i] = 1

dfs(1)
print(sum)