#include<bits/stdc++.h>
#define Gc() getchar() 
#define Me(x,y) memset(x,y,sizeof(x))
#define Mc(x,y) memcpy(x,y,sizeof(x))
#define d(x,y) ((m)*(x-1)+(y))
#define R(n) (rnd()%(n)+1)
#define Pc(x) putchar(x)
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
using namespace std;using ll=long long;using db=double;using lb=long db;using ui=unsigned;using ull=unsigned long long;using pii=pair<int,int>;using LL=__int128;
const int N=2e3+5,M=N*100+5,K=600+5,mod=998244353,Mod=mod-1;const db eps=1e-6;const int INF=1e9+7;mt19937 rnd(263082);
int S,T,x,y,n,m;vector<int> G[N];
struct yyy{int to,w,z;};struct ljb{int head=1,h[N];yyy f[M];void add(int x,int y,int z){f[++head]=(yyy){y,z,h[x]};h[x]=head;}}s;
void con(int x,int y,int z){s.add(x,y,z);s.add(y,x,0);}
int vis[N];
namespace Dicnic{
	int d[N],Ns[N];
	int bfs(){
		queue<int> q;Me(d,0x3f);Mc(Ns,s.h);d[S]=0;q.push(S);
		while(!q.empty()){
			int x=q.front();q.pop();yyy tmp;
			for(int i=s.h[x];i;i=tmp.z){
				tmp=s.f[i];if(tmp.w&&d[tmp.to]>d[x]+1) q.push(tmp.to),d[tmp.to]=d[x]+1;
			}
		}
		return d[T]<INF;
	}
	int dfs(int x,int Sum){
		if(x==T) return Sum;yyy tmp;int k,pus=0;
		for(int &i=Ns[x];i;i=tmp.z){
			tmp=s.f[i];if(!tmp.w||d[tmp.to]!=d[x]+1) continue;k=dfs(tmp.to,min(tmp.w,Sum));
			if(!k) d[tmp.to]=INF;s.f[i].w-=k;s.f[i^1].w+=k;pus+=k;Sum-=k;if(!Sum) break;
		}
		return pus;
	}
	int calc(){int ans=0;while(bfs()) ans+=dfs(S,INF);return ans;}
	void find(int x){//cerr<<"find "<<x<<'\n';
		if(vis[x]) return;vis[x]=1;yyy tmp;
		for(int i=s.h[x];i;i=tmp.z) tmp=s.f[i],tmp.w&&(find(tmp.to),0);
	}
}
char c[N],t[N];int col[N];
void dfs(int x,int w){if(col[x]||vis[x]^vis[x+n]) return;col[x]=w;for(int i:G[x]) dfs(i,-w);}
char ans[N];
void Solve(){
	int i,j;scanf("%d%d%s%s",&n,&m,c+1,t+1);S=0;T=2*n+1;
	while(m--) scanf("%d%d",&x,&y),G[x].emplace_back(y),G[y].emplace_back(x),con(x+n,y,INF),con(y+n,x,INF);
	for(i=1;i<=n;i++) if(t[i]^'?'&&!col[i]) dfs(i,t[i]^'B'?1:-1);
	for(i=1;i<=n;i++) con(i,i+n,1);
	for(i=1;i<=n;i++) if(t[i]^'?'){
		if(col[i]*(t[i]^'B'?1:-1)>0) con(S,i,INF)/*,cerr<<"S "<<i<<'\n'*/;else con(i+n,T,INF)/*,cerr<<"T "<<i<<'\n'*/;
	}
	cerr<<Dicnic::calc()<<'\n';
	Dicnic::find(S);
	Me(col,0);for(i=1;i<=n;i++) if(vis[i]==vis[i+n]&&t[i]^'?') dfs(i,t[i]^'B'?1:-1);
	for(i=1;i<=n;i++) if(vis[i]==vis[i+n]&&!col[i]) dfs(i,1);
	for(i=1;i<=n;i++) if(vis[i]^vis[i+n]) ans[i]='X';else ans[i]=(~col[i]?'A':'B');
	printf("%s\n",ans+1);
}
int main(){
	int t=1;
	// scanf("%d",&t);
	while(t--) Solve();
	cerr<<clock()*1.0/CLOCKS_PER_SEC<<'\n';
}