#include <bits/stdc++.h> using namespace std; #define fi first #define se second #define pb push_back #define ll long long #define ld long double #define mp make_pair const int inf=1e9; void chmx(int &x,int y){x=max(x,y);} void chmn(int &x,int y){x=min(x,y);} int main(){ int n;scanf("%i",&n);n*=2; int a[2][n+10]; for(int i=0;i<=1;i++) for(int j=0;j<n;j++) scanf("%i",&a[i][j]); int maks[2][n+10],mn[2][n+10]; maks[0][0]=mn[0][0]=1; maks[1][0]=mn[1][0]=-1; for(int i=1;i<n;i++){ maks[0][i]=-inf; mn[0][i]=inf; if(a[0][i-1]<=a[0][i]) chmx(maks[0][i],maks[0][i-1]+1),chmn(mn[0][i],mn[0][i-1]+1); if(a[1][i-1]<=a[0][i]) chmx(maks[0][i],maks[1][i-1]+1),chmn(mn[0][i],mn[1][i-1]+1); maks[1][i]=-inf; mn[1][i]=inf; if(a[0][i-1]<=a[1][i]) chmx(maks[1][i],maks[0][i-1]-1),chmn(mn[1][i],mn[0][i-1]-1); if(a[1][i-1]<=a[1][i]) chmx(maks[1][i],maks[1][i-1]-1),chmn(mn[1][i],mn[1][i-1]-1); } int x=-1,y=n-1; if(mn[0][n-1]<=0&&0<=maks[0][n-1]) x=0; if(mn[1][n-1]<=0&&0<=maks[1][n-1]) x=1; if(x==-1) printf("-1\n"); else{ string res; int sum=0; while(y>=0){ if(x==0) sum++; else sum--; if(x==0) res.pb('A'); else res.pb('B'); if(y<=0)break; if(a[0][y-1]<=a[x][y]&&mn[0][y-1]+sum<=0&&0<=maks[0][y-1]+sum)x=0,y--; else if(a[1][y-1]<=a[x][y]&&mn[1][y-1]+sum<=0&&0<=maks[1][y-1]+sum)x=1,y--; else break; } reverse(res.begin(),res.end()); cout<<res<<endl; } return 0; }

building4.cpp: In function 'int main()':
building4.cpp:13:16: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |     int n;scanf("%i",&n);n*=2;
      |           ~~~~~^~~~~~~~~
building4.cpp:15:53: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |     for(int i=0;i<=1;i++) for(int j=0;j<n;j++) scanf("%i",&a[i][j]);
      |                                                ~~~~~^~~~~~~~~~~~~~~