#include<bits/stdc++.h>
using namespace std;
int n,m;
string s1,s2;
char a[]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
int main(){
	int cnt1=0,f=0;
	cin>>n>>m>>s1>>s2;
	for(int i=0;i<n;i++){
		if(s1[i]=='#'){
			int b=(cnt1-1)%26+1;
			s1[i]=a[b];
			if(a[b]=='a')f=1;
			++cnt1;
		}
	}
	if(f==1){
		cout<<s1;
		return 0;
	}
	for(int i=0;i<n;i++){
		if(s2[i]=='#'){
			int b=(cnt1-1)%26+1;
			s2[i]=a[b];
			if(a[b]=='a')f=1;
			++cnt1;
		}
	}
	cout<<s2;
	return 0;
}