Gym 313459H

#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define ll long long

template<typename T>
inline void read(T&x){
    x=0;T k=1;char gc;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c)){x=x*10+c-'0';gc;}x*=k;
}

const int N=61;

ll F[N][N][N*N];
bool vis[N][N][N*N];

ll f(int n,int c,int k){
    if(!n && !k)return 1;
    if(!n || k<0)return 0;
    if(vis[n][c][k])return F[n][c][k];
    vis[n][c][k]=1;
    return F[n][c][k]=f(n-1,c,k-c)+f(n-1,c+1,k);
}

void print(int n,int c,int k,ll x){
    if(!n)return ;
    if(x<f(n-1,c,k-c)){
        putchar('A');
        print(n-1,c,k-c,x);
    }
    else {
        putchar('B');
        print(n-1,c+1,k,x-f(n-1,c,k-c));
    }
}

int main(){
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    int n,k;r(n),r(k);
    ll ans=f(n,0,k);
    if(ans&1)print(n,0,k,ans>>1);
    else {
        print(n,0,k,(ans>>1)-1);
        puts("");
        print(n,0,k,ans>>1);
    }
    puts("");
    return 0;
}