#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 11, M = 5e5 + 11, oo = ~0u >> 2;
char s[M];
int n, a[N], b[N];
int ansx, ansy;
int chk(int w) {
  int x = 0, y = 0;
  int X = oo, Y = oo;
  int u = -oo, v = oo;
  int i;
  for (i = 1; i <= n; ++i) {
    x = max(x, a[i] - w);
    y = max(y, b[i] - w);
    X = min(X, a[i] + w);
    Y = min(Y, b[i] + w);
    u = max(u, b[i] - a[i] - w);
    v = min(v, b[i] - a[i] + w);
  }
  if (x > X || y > Y || u > v) return 0;
  for (ansx = x; ansx <= X; ++ansx) {
    int yy = u + ansx;
    int YY = v + ansx;
    int _y = max(yy, y);
    int _Y = min(YY, Y);
    if (_y <= _Y && (_Y || ansx)) {
      ansy = _Y;
      return 1;
    }
  }
  return 0;
}
int main() {
  ios::sync_with_stdio(0);
  cin >> n;
  int i, j, mx = 0;
  for (i = 1; i <= n; ++i) {
    cin >> s;
    int l = strlen(s), t = 0;
    mx = max(mx, l);
    for (j = 0; j < l; ++j) {
      t += s[j] == 'B';
    }
    a[i] = t;
    b[i] = l - t;
  }
  int l = 0, r = mx + 1;
  while (l < r) {
    int m = l + r >> 1;
    if (chk(m))
      r = m;
    else
      l = m + 1;
  }
  printf("%d\n", l);
  chk(l);
  for (i = 1; i <= ansx; ++i) putchar('B');
  for (i = 1; i <= ansy; ++i) putchar('N');
  puts("");
}
