import std.stdio, std.conv, std.functional, std.string;
import std.algorithm, std.array, std.container, std.range, std.typecons;
import std.numeric, std.math, std.random;
import core.bitop;

string FMT_F = "%.10f";

static string[] s_rd;
T RD(T = long)() { while(!s_rd.length) s_rd = readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; }
string RDR()() { return readln.chomp; }
T[] ARR(T = long)(in string str, T fix = 0) { auto r = str.split.to!(T[]); r[] += fix; return r; }
size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;}
size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; }

bool inside(T)(T x, T b, T e) { return x >= b && x < e; }
long lcm(long x, long y) { return x * y / gcd(x, y); }

long mod = 10^^9 + 7;
//long mod = 998244353;
//long mod = 1_000_003;
void moda(ref long x, long y) { x = (x + y) % mod; }
void mods(ref long x, long y) { x = ((x + mod) - (y % mod)) % mod; }
void modm(ref long x, long y) { x = (x * y) % mod; }

void main()
{
	auto n = RD!int;
	auto s = new string[](n);
	int[2][][int] info1;
	int[2][][int] info2;
	auto toNum = ['a':0, 'i':1, 'u':2, 'e':3, 'o':4];
	foreach (i; 0..n)
	{
		s[i] = RD!string;
		int last;
		int cnt;
		foreach (c; s[i])
		{
			auto num = toNum.get(c, -1);
			if (num != -1)
			{
				++cnt;
				last = num;
			}
		}
		info1[cnt]         ~= [i, last];
		info2[cnt*10+last] ~= [i, last];
	}

	int[] ansSec;
	auto used = new bool[](n);
	auto keys2 = info2.keys;
	foreach (key2; keys2)
	{
		auto arr2 = info2[key2];
		auto len2 = arr2.length;
		foreach (i; 0..len2/2)
		{
			auto j  = arr2[i*2][0];
			auto k  = arr2[i*2+1][0];
			ansSec ~= [j, k];
			used[j] = true;
			used[k] = true;
		}
	}

	int[] ansFst;
	auto keys1 = info1.keys;
	foreach (key1; keys1)
	{
		auto arr1 = info1[key1];
		auto len1 = arr1.length;
		int[] tmp;
		foreach (i; 0..len1)
		{
			auto j  = arr1[i][0];
			if (used[j]) continue;

			tmp ~= j;
			if (tmp.length == 2)
			{
				ansFst ~= tmp;
				tmp.length = 0;
			}
		}
	}

	auto diff = max(0, (cast(int)ansSec.length - cast(int)ansFst.length) / 4);
	foreach (i; 0..diff)
	{
		ansFst ~= [ansSec[$-2], ansSec[$-1]];
		ansSec.length = ansSec.length - 2;
	}

	auto len = min(ansFst.length, ansSec.length);
	writeln(len/2);
	foreach (i; 0..len)
	{
		auto j = ansFst[i];
		auto k = ansSec[i];
		writeln(s[j], " ", s[k]);
	}
	stdout.flush();
	debug readln();
}