#include<bits/stdc++.h>
using namespace std;
long long a[100005],f[100005];
long long t,n,m,ans;
signed main(){
	freopen("dinner.in","r",stdin);
    freopen("dinner.out","w",stdout);
	cin>>n>>m>>t;
	for(long long i=1;i<=m;i++){
		cin>>a[i];
	}
	sort(a+1,a+m+1);
	for(long long i=1;i<m;i++){
		if((a[m]-a[i])%t!=0){
			f[i]=(a[m]-a[i])/t+1;
			ans=(a[m]-a[i])/t+1+ans;
		} 
		else{
			f[i]=(a[m]-a[1])/t;
			ans=(a[m]-a[i])/t+ans;
		}
		if(ans>n){
			break;
		}
	}
	long long nxt=m;
	while(ans<n){
		f[nxt]+=1;
		nxt++;
		nxt=nxt%m;
		ans+=1;
	}
	long long maxn=-1;
	for(long long i=1;i<=m;i++){
	   maxn=max(maxn,a[i]+t*f[i]);
	}
	cout<<maxn;
	return 0;
}