#include <bits/stdc++.h>   const int mod = 200003;   const int gmod = 2;   const int inf = 1039074182;   const long long llinf = 1LL * inf * inf;   template <typename T1, typename T2>   inline void chmin(T1 &x, T2 b) {     if (b < x) x = b;   }   template <typename T1, typename T2>   inline void chmax(T1 &x, T2 b) {     if (b > x) x = b;   }   template <typename T1, typename T2>   inline void chadd(T1 &x, T2 b) {     x += b;     if (x >= mod) x -= mod;   }   template <typename T1, typename T2>   inline void chmul(T1 &x, T2 b) {     x = 1LL * x * b % mod;   }   template <typename T1, typename T2>   inline void chmod(T1 &x, T2 b) {     x %= b, x += b;     if (x >= b) x -= b;   }   using namespace std;   template <typename T>   ostream &operator<<(ostream &cout, vector<T> vec) {     cout <<  { ;     for (int i = 0; i < vec.size(); i++) {       cout << vec[i];       if (i != (int)vec.size() - 1) cout <<  , ;     }     cout <<  } ;     return cout;   }   template <typename T1, typename T2>   ostream &operator<<(ostream &cout, pair<T1, T2> p) {     cout <<  (  << p.first <<  ,  << p.second <<  ) ;     return cout;   }   template <typename T>   ostream &operator<<(ostream &cout, set<T> s) {     vector<T> t;     for (auto x : s) t.push_back(x);     cout << t;     return cout;   }   template <typename T>   ostream &operator<<(ostream &cout, queue<T> q) {     vector<T> t;     while (q.size()) {       t.push_back(q.front());       q.pop();     }     cout << t;     return cout;   }   template <typename T1, typename T2>   ostream &operator<<(ostream &cout, map<T1, T2> m) {     for (auto &x : m) {       cout <<  Key:   << x.first <<     <<  Value:   << x.second << endl;     }     return cout;   }   template <typename T>   T operator*(vector<T> v1, vector<T> v2) {     assert(v1.size() == v2.size());     int n = v1.size();     T res = 0;     for (int i = 0; i < n; i++) {       res += v1[i] * v2[i];     }     return res;   }   template <typename T1, typename T2>   pair<T1, T2> operator+(pair<T1, T2> x, pair<T1, T2> y) {     return make_pair(x.first + y.first, x.second + y.second);   }   template <typename T1, typename T2>   pair<T1, T2> operator-(pair<T1, T2> x) {     return make_pair(-x.first, -x.second);   }   template <typename T>   vector<vector<T> > operator~(vector<vector<T> > vec) {     vector<vector<T> > v;     int n = vec.size(), m = vec[0].size();     v.resize(m);     for (int i = 0; i < m; i++) {       v[i].resize(n);     }     for (int i = 0; i < m; i++) {       for (int j = 0; j < n; j++) {         v[i][j] = vec[j][i];       }     }     return v;   }   void print0x(int x) {     std::vector<int> vec;     while (x) {       vec.push_back(x & 1);       x >>= 1;     }     std::reverse(vec.begin(), vec.end());     for (int i = 0; i < vec.size(); i++) {       std::cout << vec[i];     }     std::cout <<    ;   }   template <typename T>   void print0x(T x, int len) {     std::vector<int> vec;     while (x) {       vec.push_back(x & 1);       x >>= 1;     }     reverse(vec.begin(), vec.end());     for (int i = vec.size(); i < len; i++) {       putchar( 0 );     }     for (int i = 0; i < vec.size(); i++) {       std::cout << vec[i];     }     std::cout <<    ;   }   using namespace std;   const int basic = 500000;   int n;   int a[300005], b[300005];   char buf[500005];   vector<int> sum[basic * 2 + 5];   int m1, m2, m3, m4;   int b1, b2;   int besta, bestb;   int best;   inline void calc(int k) {     int res = 0;     chmax(res, b1);     chmax(res, b2);     int zx = max(m2, m3);     int nx = max(m1, m4);     int tx = (nx - zx) / 2;     chmax(tx, 0);     chmax(res, -tx + nx);     if (res < best) {       best = res;       besta = tx;       if (besta == 0 && k == 0) besta++;       bestb = besta + k;     }   }   inline void read(int &a, int &b) {     a = 0;     b = 0;     char c = 0;     while (c !=  N  && c !=  B ) c = getchar();     while (c ==  N  || c ==  B ) {       if (c ==  B )         b++;       else         a++;       c = getchar();     }   }   int main() {     cin >> n;     m1 = -inf, m2 = -inf, m3 = -inf, m4 = -inf;     b1 = -inf, b2 = -inf;     int k = basic;     for (int i = 0; i < n; i++) {       read(a[i], b[i]);       sum[b[i] - a[i] + basic].push_back(i);       chmax(b2, a[i] + k - b[i]);       chmax(m3, k - b[i]);       chmax(m4, a[i]);     }     best = inf;     calc(basic);     for (k = basic - 1; k >= -basic; k--) {       m1++;       b1++;       m3--;       b2--;       for (auto id : sum[k + basic]) {         int x0 = a[id];         int y0 = b[id];         chmax(m1, y0 - k);         chmax(m2, -x0);         chmax(b1, y0 - (x0 + k));       }       calc(k);     }     cout << best << endl;     for (int i = 0; i < bestb; i++) {       putchar( B );     }     for (int i = 0; i < besta; i++) {       putchar( N );     }     return 0;   }