#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef vector<vector<long long>> VVL;
typedef pair<int,int> Pair;
typedef tuple<int,int,int> tpl;

#define ALL(a)  (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define REVERSE(c) reverse((c).begin(),(c).end())
#define EXIST(m,v) (m).find((v)) != (m).end()
#define LB(a,x) lower_bound((a).begin(), (a).end(), x) - (a).begin()
#define UB(a,x) upper_bound((a).begin(), (a).end(), x) - (a).begin()

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define RFOR(i,a,b) for(int i=(a)-1;i>=(b);--i)
#define RREP(i,n) RFOR(i,n,0)

#define en "\n"

constexpr double EPS = 1e-9;
constexpr double PI  = 3.1415926535897932;
constexpr int INF = 2147483647;
constexpr long long LINF = 1LL<<60;
constexpr long long MOD = 1000000007; // 998244353;

template<class T> inline bool chmax(T& a, T b){if(a<b){a=b;return true;}return false;}
template<class T> inline bool chmin(T& a, T b){if(a>b){a=b;return true;}return false;}

VVI c = {{1,0,0},{1,1,0},{1,2,1}};

int Lucas(int n, int r, int mod=3){
    int ret = 1;
    while(n || r){
        int x = n%mod, y = r%mod;
        (ret *= c[x][y]) %= mod;
        n /= mod; r /= mod;
    }
    return ret;
}

void Main(){
    int N; cin >> N;
    int ans = 0;
    REP(i,N){
        char c; cin >> c;
        int m;
        if(c=='B') m = 0;
        else if(c=='W') m = 1;
        else m = 2;

        (ans += Lucas(N-1,i)*m) %= 3;
    }

    if((N-1)&1){
        ans *= -1;
        if(ans<0) ans += 3;
    }

    cout << "BWR"[ans] << en;
    return;
}

int main(void){
    cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(0);cout<<fixed<<setprecision(15);
    int t=1; //cin>>t;
    while(t--) Main();
    return 0;
}
#include <bits/stdc++.h>
using namespace std;
 
using ll = long long;
using pii = pair<int, int>;
template <class T>
using V = vector<T>;
template <class T>
using VV = V<V<T>>;
 
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define rep(i, n) rep2(i, 0, n)
#define rep2(i, m, n) for (int i = m; i < (n); i++)
#define per(i, b) per2(i, 0, b)
#define per2(i, a, b) for (int i = int(b) - 1; i >= int(a); i--)
#define ALL(c) (c).begin(), (c).end()
#define SZ(x) ((int)(x).size())
 
constexpr ll TEN(int n) { return (n == 0) ? 1 : 10 * TEN(n - 1); }
 
template <class T, class U>
void chmin(T& t, const U& u) {
    if (t > u) t = u;
}
template <class T, class U>
void chmax(T& t, const U& u) {
    if (t < u) t = u;
}
 
template <class T, class U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
    os << "(" << p.first << "," << p.second << ")";
    return os;
}
 
template <class T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    os << "{";
    rep(i, v.size()) {
        if (i) os << ",";
        os << v[i];
    }
    os << "}";
    return os;
}
 
#ifdef LOCAL
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << " " << H;
    debug_out(T...);
}
#define debug(...) \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif
 
int main() {
    int N;
    cin >> N;
    V<int> A(N), B(N);
    int sz = N * 2;
    V<int> tp(sz), com(sz, -1);
 
    bool ng = false;
 
    rep(i, N) {
        cin >> A[i] >> B[i];
        if (A[i] != -1) {
            --A[i];
            if (tp[A[i]]) ng = true;
            tp[A[i]] = i + 1;
        }
        if (B[i] != -1) {
            --B[i];
            if (tp[B[i]]) ng = true;
            tp[B[i]] = -(i + 1);
        }
 
        if (A[i] != -1 && B[i] != -1) {
            com[A[i]] = B[i];
            com[B[i]] = A[i];
        }
    }
    if (ng) {
        puts("No");
        return 0;
    }
 
    V<bool> dp(sz + 1);
    dp[0] = true;
 
    rep(i, sz) {
        if (!dp[i]) continue;
        for (int j = i + 1; j < sz; ++j) {
            int w = j - i + 1;
            if (w & 1) continue;
            w /= 2;
            bool ok = true;
            V<bool> exist(N);
 
            rep(k, w) {
                int p = i + k, q = i + k + w;
                if (com[p] != -1 && !(i <= com[p] && com[p] <= j)) {
                    ok = false;
                }
                if (com[q] != -1 && !(i <= com[q] && com[q] <= j)) {
                    ok = false;
                }
 
                bool same = true;
                if (tp[p] != 0 && tp[q] != 0) {
                    if (tp[p] < 0 || tp[p] + tp[q] != 0) {
                        ok = false;
                    } else
                        same = true;
                }
                if (tp[p] < 0 || tp[q] > 0) {
                    ok = false;
                } else {
                    if (tp[p] != 0) {
                        int v = tp[p] - 1;
                        if (exist[v]) {
                            ok = false;
                        }
                        exist[v] = true;
                    }
                }
            }
            if (ok) {
                dp[j + 1] = true;
            }
        }
    }
    puts(dp[sz] ? "Yes" : "No");
 
    return 0;
}
