#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

#define rd() ({long _v=0,_c;while(_c=*rp++-48,_c>=0)_v=_v*10+_c;_v;})
#define wt(v) {ulong _z=v;do*--wp=_z%10+48;while(_z/=10);}
#define rep(v,e) for(long v=0;v<e;++v)
#define rep3(v,s,e) for(long v=s;v<e;++v)
#define chmin(v,a) (v=v<=a?v:a)

typedef unsigned long ulong;

ulong c[5000];
ulong d[2000];
long e[2000];

void f0(){
	rep(i,2000){
		e[i]=1l<<61;
	}
}

long f1(ulong n){
	long dn=0;
	for(ulong i=1;i*i<=n;++i){
		if(n%i==0){
			d[dn]=i;
			++dn;
		}
	}
	for(ulong i=dn-(d[dn-1]*d[dn-1]==n);i--;){
		d[dn++]=n/d[i];
	}
	return dn;
}

ulong f2(long dn,long a,long m){
	rep(i,dn){
		if(e[i]<1l<<61){
			long t=1l<<61;
			rep(j,m){
				if(c[j]<t&&c[j]%d[i]==0){
					t=c[j];
				}
			}
			rep3(j,i+1,dn){
				if(d[j]>=t){
					break;
				}
				if(d[j]%d[i]==0){
					long x=e[i]-e[0]+a*(d[j]/d[i]-1);
					chmin(e[j],x);
				}
			}
		}
	}
	return e[dn-1];
}

void f3(ulong z){
	char wbuf[64],*wp=wbuf+sizeof wbuf;
	if(z==1l<<61){
		*--wp='1';
		*--wp='-';
	}else{
		wt(z);
	}
	write(1,wp,wbuf+sizeof wbuf-wp);
}

int main(){
	f0();
	long n,m,a;
	{
		char*mmap();
		char*rp=mmap(0l,1l<<25,1,2,0,0ll);
		n=rd();
		m=rd();
		a=rd();
		e[0]=-rd();
		rep(i,m){
			c[i]=rd();
		}
	}
	f3(f2(f1(n),a,m));
	_exit(0);
}