n = int(input())
a = list(map(int, input().split()))
b = list(zip(a, range(2 * n)))
b.sort()

ans = 0
pair = []
for i in range(n):
    ans += b[~i][0] - b[i][0]
    pair.append((b[~i][1] + 1, b[i][1] + 1))
print(ans)
for x, y in pair:
    print(x, y)