#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include <bits/stdc++.h>
using namespace std;
typedef long long lo;
typedef pair< lo,lo > PII;
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define fio() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define FOR for(int i=1;i<=n;i++)
#define mid ((start+end)/2)
#define ort ((bas+son)/2)
const lo MAX = -1000000000000000000;
const lo MIN = 1000000000000000000;
const lo inf = 1000000000;
const lo KOK = 100000;
const lo LOG = 30;
const lo li = 500005;
const lo mod = 1000000007;
int n,m,b[li],a[li],k,flag,t;
int cev;
string s,ss;
vector<int> v;
int main(void){
cin>>n>>m>>k>>t;
cin>>s>>ss;
sort(ss.begin(),ss.end());
for(int i=0;i<(int)s.size();i++){
if(s[i]=='#')s[i]=ss[t-1];
}
cout<<s<<endl;
return 0;
}
