1
n = int(input())
2
a = [int(x) for x in input().split()]
3
p = []
4
m = []
5
s = []
6
 
7
for i in range(n):
8
    if a[i] == 1:
9
        p.append(i + 1)
10
    elif a[i] == 2:
11
        m.append(i + 1)
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    else:
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        s.append(i + 1)
14
    
15
k = min(len(p), len(m), len(s))
16
print(k)
17
for i in range(k):
18
    print(p[i], m[i], s[i])