#include <stdio.h>
#include <algorithm>
#include <queue>

using namespace std;

struct node {
	int v , f , i , tp;
	node *next , *rev;
} pool[210000] , *g[12000];
int top;
int n , m;
char z[1200] , ss[1200];
int s , t;
int lev[12000];
int ans , cnt;
int taboo[12000] , vis[12000];
char out[12000] , oth[122];
void add ( int u , int v , int f , int i , int tp ) {
	node *tmp1 = &pool[++top] , *tmp2 = &pool[++top];
	tmp1 -> v = v; tmp1 -> f = f; tmp1 -> next = g[u]; g[u] = tmp1; tmp1 -> rev = tmp2;
	tmp1 -> i = i; tmp1 -> tp = tp;
	tmp2 -> v = u; tmp2 -> f = 0; tmp2 -> next = g[v]; g[v] = tmp2; tmp2 -> rev = tmp1;
}
bool makelevel () {
	int i , k;
	queue < int > q;
	for ( i = 1 ; i <= t ; i++ ) {
		lev[i] = -1;
	}
	lev[s] = 1;
	q.push ( s );
	while ( q.size () ) {
		k = q.front (); q.pop ();
		for ( node *j = g[k] ; j ; j = j -> next )
			if ( j -> f && lev[j->v] == -1 ) {
				lev[j->v] = lev[k] + 1;
				q.push ( j -> v );
				if ( j -> v == t ) return true;
			}
	}
	return false;
}
int find ( int k , int key ) {
	if ( k == t ) return key;
	int i , s = 0;
	for ( node *j = g[k] ; j ; j = j -> next ) {
		if ( j -> f && s < key && lev[j->v] == lev[k] + 1 ) {
			i = find ( j -> v , min ( key - s , j -> f ) );
			j -> f -= i;
			j -> rev -> f += i;
			s += i;
		}
	}
	if ( s == 0 ) lev[k] = -1;
	return s;
}
void dinic () {
	ans = 0;
	while ( makelevel () == true ) ans += find ( s , 1111111 );
}
void dfs ( int i , int from ) {
	if ( vis[i] ) return ;
	vis[i] = 1;
	for ( node *j = g[i] ; j ; j = j -> next ) {
		if ( j -> f && j -> v != from ) {
			dfs ( j -> v , i );
		}
	}
}
void work () {
	int i , u , v;
	scanf ( "%d%d" , &n , &m );
	scanf ( "%s" , z + 1 );
	scanf ( "%s" , ss + 1 );
	s = 1; t = 1 + n + n + 1;
	for ( i = 1 ; i <= n ; i++ ) {
		if ( ss[i] == '?' ) {
			add ( s , 1 + i , 1 , i , 1 );
			add ( 1 + i , 1 + n + i , 1111111 , 0 , 0 );
			add ( 1 + n + i , t , 1 , i , 2 );
			cnt++;
		}
		else {
			if ( ss[i] == z[i] ) {
				add ( s , 1 + i , 1 , i , 1 );
			}
			else {
				add ( 1 + n + i , t , 1 , i , 2 );
			}
		}
	}
	for ( i = 1 ; i <= m ; i++ ) {
		scanf ( "%d%d" , &u , &v );
		add ( 1 + u , 1 + n + v , 111111 , 0 , 0 );
		add ( 1 + v , 1 + n + u , 111111 , 0 , 0 );
	}
	dinic ();
	oth['A'] = 'B';
	oth['B'] = 'A';
	for ( i = 1 ; i <= n ; i++ ) {
		out[i] = 'X';
	}
	dfs ( s , -1 );
	for ( i = s ; i <= t ; i++ ) {
		if ( vis[i] == 1 ) {
			for ( node *j = g[i] ; j ; j = j -> next ) {
				if ( vis[j->v] == 0 && j -> i != 0 ) {
					taboo[j->i] |= j -> tp;
				}
			}
		}
	}
	for ( i = 1 ; i <= n ; i++ ) {
		if ( ss[i] == '?' ) {
			if ( taboo[i] == 3 ) {
				out[i] = 'X';
			}
			else {
				if ( taboo[i] == 1 ) {
					out[i] = oth[z[i]];
				}
				else out[i] = z[i];
			}
		}
		else {
			if ( taboo[i] ) {
				out[i] = 'X';
			}
			else {
				out[i] = ss[i];
			}
		}
	}
	/*for ( i = 1 ; i <= t ; i++ ) {
		printf ( "%d:\n" , i );
		for ( node *j = g[i] ; j ; j = j -> next ) {
			printf ( "   %d %d\n" , j -> v , j -> f );
		}
	}*/
	printf ( "%s\n" , out + 1 );
}
int main () {
	work ();
	return 0;
}