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#include <stdio.h>
#include <bitset>
#define MAX(a,b) (((a)>(b))?(a):(b))
using ll=long long;
const int C=100001, D=10001, Inf=1000000001;

ll a[C], b[C], dp[C], tmp_dp[C];
std::bitset<D> res[C];
bool exists[C], tmp_exists[C];
bool check_validity(ll m, int n, int k){
	int i, j;

	for (j=0; j<=k; j++) exists[j] = false, tmp_exists[j]=false;
	exists[0]=true;
	dp[0]=0;

	for (i=1; i<=n; i++){
		for (j=0; j<=k; j++){
			if (exists[j] && dp[j]+b[i] <= m){
			       	tmp_exists[j] = true;
			      	tmp_dp[j] = MAX(dp[j]+b[i], 0);
				res[i][j] = 0;
			}

			if (j>0 && exists[j-1] && dp[j-1]+a[i] <= m && ((!tmp_exists[j]) || (dp[j-1]+a[i] < tmp_dp[j]))){
				tmp_exists[j] = true;
				tmp_dp[j] = MAX(dp[j-1]+a[i], 0);
				res[i][j] = true;
			}
		}

		for (j=0; j<=k; j++){
			dp[j] = tmp_dp[j];
			exists[j] = tmp_exists[j];
			tmp_exists[j] = false;
		}
	}
	return exists[k];
}

int to_fill[C];
int main(){
	int n, k, i;
	bool inv=false;

	scanf ("%d %d", &n, &k);
	if (k > n/2) inv=true, k=n-k;
	if (!inv){
		for (i=1; i<=n; i++) scanf ("%lld", &a[i]);
		for (i=1; i<=n; i++) scanf ("%lld", &b[i]);
	}
	else{
		for (i=1; i<=n; i++) scanf ("%lld", &b[i]);
		for (i=1; i<=n; i++) scanf ("%lld", &a[i]);
	}

	ll l=0, r=1ll*n*Inf, m;
	while (l<=r){
		m = (l+r)/2;
		if (check_validity(m, n, k)) r=m-1;
		else l=m+1;
	}

	ll vv = l;
	int cur=k;
	printf ("%lld\n", vv);
	check_validity(vv, n, k);

	for (i=n; i>0; i--) {
		to_fill[i] = res[i][cur];
		cur = cur-to_fill[i];
	}
	if (!inv){
		for (i=1; i<=n; i++) printf ("%c", ((to_fill[i]==0)?('B'):('A')));
	}
	else{
		for (i=1; i<=n; i++) printf ("%c", ((to_fill[i]==0)?('A'):('B')));
	}
	printf ("\n");

return 0;}