#include <bits/stdc++.h> using namespace std; #define int long long #define ld long double #define pii pair<int, int> #define fi first #define se second #define __builtin_popcount __builtin_popcountll #define all(x) (x).begin(), (x).end() #define BIT(x, i) (((x) >> (i)) & 1) #define MASK(x) ((1ll << (x))) #define debug(a, l, r) for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n'; const int MAXN = 1e6 + 6; const int INF = 1e18 + 7; int n, a[MAXN][2], dpmx[MAXN][2], dpmi[MAXN][2]; void init() { cin >> n; n *= 2; for (int i = 1; i <= n; ++i) cin >> a[i][0]; for (int i = 1; i <= n; ++i) cin >> a[i][1]; } void solve() { dpmx[1][0] = dpmi[1][0] = 1; dpmx[1][1] = dpmi[1][1] = -1; for (int i = 2; i <= n; ++i) { for (int cur = 0; cur < 2; ++cur) { dpmx[i][cur] = -INF; dpmi[i][cur] = INF; for (int pre = 0; pre < 2; ++pre) { int weight = (cur == 0 ? 1 : -1); if (a[i - 1][pre] <= a[i][cur]) { if (dpmx[i - 1][pre] != -INF) dpmx[i][cur] = max(dpmx[i][cur], dpmx[i - 1][pre] + weight); if (dpmi[i - 1][pre] != INF) dpmi[i][cur] = min(dpmi[i][cur], dpmi[i - 1][pre] + weight); } } } // cout << dpmi[i][0] << ' ' << dpmx[i][0] << '\n'; // cout << dpmi[i][1] << ' ' << dpmx[i][1] << '\n'; // cout << '\n'; } // Trace int en = -1; if (dpmi[n][0] <= 0 && 0 <= dpmx[n][0]) en = 0; else if (dpmi[n][1] <= 0 && 0 <= dpmx[n][1]) en = 1; if (en == -1) { cout << -1; return; } int sum = 0, pos = n, state = en; vector<int> res; while (pos >= 1) { res.push_back(state); int weight = (state == 0 ? 1 : -1); sum -= weight; --pos; if (a[pos][0] <= a[pos+1][state] && dpmi[pos][0] <= sum && sum <= dpmx[pos][0]) state = 0; else if (a[pos][1] <= a[pos+1][state] && dpmi[pos][1] <= sum && sum <= dpmx[pos][1]) state = 1; } reverse(all(res)); for (int u : res) cout << (u ? 'B' : 'A'); } signed main() { #ifdef NCTHANH freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout); #endif ios_base::sync_with_stdio(0); cin.tie(nullptr); cout.tie(nullptr); init(); solve(); return 0; }