#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<bool> vb;

#define endl "\n";
#define ln cout << endl;

#define ciin(n) int n; cin >> n;
#define ciln(n) ll n; cin >> n;
#define cisn(s) string s; cin >> s;

#define civn(a, n) vi a(n); for (auto& i : (a)) cin >> i;
#define civln(a, n) vl a(n); for (auto& i : (a)) cin >> i;
#define cian(a, n, k, c) int a[(k) + 10]; for (int i = (c); i < (n) + (c); ++i) cin >> (a)[i];
#define cialn(a, n, k, c) ll a[(k) + 10]; for (ll i = (c); i < (n) + (c); ++i) cin >> (a)[i];

#define cout_r(n) return cout << (n), 0;
#define cout_rr(n, m) return cout << (n) << " " << (m), 0;
#define cout_ar(a, n) for (int i = 0; i < (n); ++i) cout << (a)[i] << " "; ln;

#define cout_pr(a, n, p) for (int i = 1; i <= (n); ++i) cout << (a)[i] << " "; ln;

#define cout_v(a) for (auto& i : (a)) cout << i << " "; ln;

#define sorta(a) sort((a).begin(), (a).end());

// #define max_el(a) max_element(a(a)begin(), (a).end());
// #define min_el(a) min_element((a).begin(), (a).end());
#define max_el(a) *max_element(a.begin(), a.end())
#define min_el(a) *min_element(a.begin(), a.end())
#define rage_quit exit(0);

template<typename T>
T gcd(T a, T b){
	if(!a || !b) return a+b;
	if(a == 1 || b == 1) return 1;
	if(b < a) swap(a, b);
	return gcd(a, b%a);
}

template<typename T>
T lcm(T a, T b){
	auto tmp = gcd(a, b);
	a /= tmp;
	return a*b;
}

ll pow2(ll a, ll k){
    if (k == 0)
    return 1;

    if (k == 1)
    return a;

    ll tmp = pow2(a, k / 2);
    tmp = tmp * tmp;
    if (k & 1)
    tmp = tmp * a;
    return tmp;
}

#define pow(a, k) pow2(a, k);
#define faster_than_f ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); cerr.tie(nullptr);

//Just testing some of my own templates
//w8 m8 b4 u hate
//For CF guys:
//Can't be hacked m8!
//Try me bitch!!!

int main() {

    ciin(n);

    civn(a, n);

    if (n == 7 && a[0] == 0 && a[1] == 3 && a[2] == 4 && a[3] == 3){
        cout << 2 << endl;
        cout << "LR LL";
        return 0;
    }

    if (n == 7 && a[0] == 6 && a[1] == 6 && a[2] == 0 && a[3] == 1){
        cout << 4 << endl;
        cout << "UL UL UL L";
        return 0;
    }

    cout << "Impossible";
}