import random, sys, os, math, gc from collections import Counter, defaultdict, deque from functools import lru_cache, reduce, cmp_to_key from itertools import accumulate, combinations, permutations, product from heapq import nsmallest, nlargest, heapify, heappop, heappush from io import BytesIO, IOBase from copy import deepcopy from bisect import bisect_left, bisect_right from math import factorial, gcd from operator import mul, xor from types import GeneratorType # if "PyPy" in sys.version: # import pypyjit; pypyjit.set_param('max_unroll_recursion=-1') # sys.setrecursionlimit(2*10**5) BUFSIZE = 8192 MOD = 10**9 + 7 MODD = 998244353 INF = float('inf') D4 = [(1, 0), (0, 1), (-1, 0), (0, -1)] D8 = [(1, 0), (1, 1), (0, 1), (-1, 1), (-1, 0), (-1, -1), (0, -1), (1, -1)] def solve(): n = II() arr = LII() def f(i, j): return (arr[i] - 1) * (arr[i + 1] - 1) if gcd(arr[i], arr[i + 1]) == 1 else 0 if n == 2: print(f(0, 1)) print(1, 2) return if n >= 4: print(0) for _ in range(n - 1): print(1, 2) return ans = [1e99, []] for lst in [(0, 1, 2), (0, 2, 1), (1, 2, 0)]: L = list(lst) for i in range(0, len(L), 2): t = f(i, i + 1) arr.append(t) L.append(len(L)) ans = min(ans, [arr[-1], lst]) print(ans[0]) if ans[1] == (0, 1, 2): print(1, 2) if ans[1] == (0, 2, 1): print(1, 3) if ans[1] == (1, 2, 0): print(2, 3) print(1, 2) def main(): t = 1 # t = II() for _ in range(t): solve() def bootstrap(f, stack=[]): def wrappedfunc(*args, **kwargs): if stack: return f(*args, **kwargs) else: to = f(*args, **kwargs) while True: if type(to) is GeneratorType: stack.append(to) to = next(to) else: stack.pop() if not stack: break to = stack[-1].send(to) return to return wrappedfunc def bitcnt(n): c = (n & 0x5555555555555555) + ((n >> 1) & 0x5555555555555555) c = (c & 0x3333333333333333) + ((c >> 2) & 0x3333333333333333) c = (c & 0x0F0F0F0F0F0F0F0F) + ((c >> 4) & 0x0F0F0F0F0F0F0F0F) c = (c & 0x00FF00FF00FF00FF) + ((c >> 8) & 0x00FF00FF00FF00FF) c = (c & 0x0000FFFF0000FFFF) + ((c >> 16) & 0x0000FFFF0000FFFF) c = (c & 0x00000000FFFFFFFF) + ((c >> 32) & 0x00000000FFFFFFFF) return c def lcm(x, y): return x * y // gcd(x, y) def lowbit(x): return x & -x def perm(n, r): return factorial(n) // factorial(n - r) if n >= r else 0 def comb(n, r): return factorial(n) // (factorial(r) * factorial(n - r)) if n >= r else 0 def probabilityMod(x, y, mod): return x * pow(y, mod-2, mod) % mod class SortedList: def __init__(self, iterable=[], _load=200): """Initialize sorted list instance.""" values = sorted(iterable) self._len = _len = len(values) self._load = _load self._lists = _lists = [values[i:i + _load] for i in range(0, _len, _load)] self._list_lens = [len(_list) for _list in _lists] self._mins = [_list[0] for _list in _lists] self._fen_tree = [] self._rebuild = True def _fen_build(self): """Build a fenwick tree instance.""" self._fen_tree[:] = self._list_lens _fen_tree = self._fen_tree for i in range(len(_fen_tree)): if i | i + 1 < len(_fen_tree): _fen_tree[i | i + 1] += _fen_tree[i] self._rebuild = False def _fen_update(self, index, value): """Update `fen_tree[index] += value`.""" if not self._rebuild: _fen_tree = self._fen_tree while index < len(_fen_tree): _fen_tree[index] += value index |= index + 1 def _fen_query(self, end): """Return `sum(_fen_tree[:end])`.""" if self._rebuild: self._fen_build() _fen_tree = self._fen_tree x = 0 while end: x += _fen_tree[end - 1] end &= end - 1 return x def _fen_findkth(self, k): """Return a pair of (the largest `idx` such that `sum(_fen_tree[:idx]) <= k`, `k - sum(_fen_tree[:idx])`).""" _list_lens = self._list_lens if k < _list_lens[0]: return 0, k if k >= self._len - _list_lens[-1]: return len(_list_lens) - 1, k + _list_lens[-1] - self._len if self._rebuild: self._fen_build() _fen_tree = self._fen_tree idx = -1 for d in reversed(range(len(_fen_tree).bit_length())): right_idx = idx + (1 << d) if right_idx < len(_fen_tree) and k >= _fen_tree[right_idx]: idx = right_idx k -= _fen_tree[idx] return idx + 1, k def _delete(self, pos, idx): """Delete value at the given `(pos, idx)`.""" _lists = self._lists _mins = self._mins _list_lens = self._list_lens self._len -= 1 self._fen_update(pos, -1) del _lists[pos][idx] _list_lens[pos] -= 1 if _list_lens[pos]: _mins[pos] = _lists[pos][0] else: del _lists[pos] del _list_lens[pos] del _mins[pos] self._rebuild = True def _loc_left(self, value): """Return an index pair that corresponds to the first position of `value` in the sorted list.""" if not self._len: return 0, 0 _lists = self._lists _mins = self._mins lo, pos = -1, len(_lists) - 1 while lo + 1 < pos: mi = (lo + pos) >> 1 if value <= _mins[mi]: pos = mi else: lo = mi if pos and value <= _lists[pos - 1][-1]: pos -= 1 _list = _lists[pos] lo, idx = -1, len(_list) while lo + 1 < idx: mi = (lo + idx) >> 1 if value <= _list[mi]: idx = mi else: lo = mi return pos, idx def _loc_right(self, value): """Return an index pair that corresponds to the last position of `value` in the sorted list.""" if not self._len: return 0, 0 _lists = self._lists _mins = self._mins pos, hi = 0, len(_lists) while pos + 1 < hi: mi = (pos + hi) >> 1 if value < _mins[mi]: hi = mi else: pos = mi _list = _lists[pos] lo, idx = -1, len(_list) while lo + 1 < idx: mi = (lo + idx) >> 1 if value < _list[mi]: idx = mi else: lo = mi return pos, idx def add(self, value): """Add `value` to sorted list.""" _load = self._load _lists = self._lists _mins = self._mins _list_lens = self._list_lens self._len += 1 if _lists: pos, idx = self._loc_right(value) self._fen_update(pos, 1) _list = _lists[pos] _list.insert(idx, value) _list_lens[pos] += 1 _mins[pos] = _list[0] if _load + _load < len(_list): _lists.insert(pos + 1, _list[_load:]) _list_lens.insert(pos + 1, len(_list) - _load) _mins.insert(pos + 1, _list[_load]) _list_lens[pos] = _load del _list[_load:] self._rebuild = True else: _lists.append([value]) _mins.append(value) _list_lens.append(1) self._rebuild = True def discard(self, value): """Remove `value` from sorted list if it is a member.""" _lists = self._lists if _lists: pos, idx = self._loc_right(value) if idx and _lists[pos][idx - 1] == value: self._delete(pos, idx - 1) def remove(self, value): """Remove `value` from sorted list; `value` must be a member.""" _len = self._len self.discard(value) if _len == self._len: raise ValueError('{0!r} not in list'.format(value)) def pop(self, index=-1): """Remove and return value at `index` in sorted list.""" pos, idx = self._fen_findkth(self._len + index if index < 0 else index) value = self._lists[pos][idx] self._delete(pos, idx) return value def bisect_left(self, value): """Return the first index to insert `value` in the sorted list.""" pos, idx = self._loc_left(value) return self._fen_query(pos) + idx def bisect_right(self, value): """Return the last index to insert `value` in the sorted list.""" pos, idx = self._loc_right(value) return self._fen_query(pos) + idx def count(self, value): """Return number of occurrences of `value` in the sorted list.""" return self.bisect_right(value) - self.bisect_left(value) def __len__(self): """Return the size of the sorted list.""" return self._len def __getitem__(self, index): """Lookup value at `index` in sorted list.""" pos, idx = self._fen_findkth(self._len + index if index < 0 else index) return self._lists[pos][idx] def __delitem__(self, index): """Remove value at `index` from sorted list.""" pos, idx = self._fen_findkth(self._len + index if index < 0 else index) self._delete(pos, idx) def __contains__(self, value): """Return true if `value` is an element of the sorted list.""" _lists = self._lists if _lists: pos, idx = self._loc_left(value) return idx < len(_lists[pos]) and _lists[pos][idx] == value return False def __iter__(self): """Return an iterator over the sorted list.""" return (value for _list in self._lists for value in _list) def __reversed__(self): """Return a reverse iterator over the sorted list.""" return (value for _list in reversed(self._lists) for value in reversed(_list)) def __repr__(self): """Return string representation of sorted list.""" return 'SortedList({0})'.format(list(self)) class FastIO(IOBase): newlines = 0 def __init__(self, file): self._fd = file.fileno() self.buffer = BytesIO() self.writable = "x" in file.mode or "r" not in file.mode self.write = self.buffer.write if self.writable else None def read(self): while True: b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE)) if not b: break ptr = self.buffer.tell() self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr) self.newlines = 0 return self.buffer.read() def readline(self): while self.newlines == 0: b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE)) self.newlines = b.count(b"\n") + (not b) ptr = self.buffer.tell() self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr) self.newlines -= 1 return self.buffer.readline() def flush(self): if self.writable: os.write(self._fd, self.buffer.getvalue()) self.buffer.truncate(0), self.buffer.seek(0) class IOWrapper(IOBase): def __init__(self, file): self.buffer = FastIO(file) self.flush = self.buffer.flush self.writable = self.buffer.writable self.write = lambda s: self.buffer.write(s.encode("ascii")) self.read = lambda: self.buffer.read().decode("ascii") self.readline = lambda: self.buffer.readline().decode("ascii") sys.stdin = IOWrapper(sys.stdin) # sys.stdout = IOWrapper(sys.stdout) input = lambda: sys.stdin.readline().rstrip("\r\n") # input = BytesIO(os.read(0, os.fstat(0).st_size)).readline def I(): return input() def II(): return int(input()) def MI(): return map(int, input().split()) def LI(): return list(input().split()) def LII(): return list(map(int, input().split())) def GMI(): return map(lambda x: int(x) - 1, input().split()) def LGMI(): return list(map(lambda x: int(x) - 1, input().split())) def getGraph(n, m, directed=False): d = [[] for _ in range(n)] for _ in range(m): u, v = LGMI() d[u].append(v) if not directed: d[v].append(u) return d def getWeightedGraph(n, m, directed=False): d = [[] for _ in range(n)] for _ in range(m): u, v, w = LII() u -= 1; v -= 1 d[u].append((v, w)) if not directed: d[v].append((u, w)) return d def YES(t = 1): print("YES" if t else "NO") def NO(t = 1): YES(t ^ 1) def Yes(t = 1): print("Yes" if t else "No") def No(t = 1): Yes(t ^ 1) def yes(t = 1): print("yes" if t else "no") def no(t = 1): yes(t ^ 1) if __name__ == "__main__": main()