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

char rbuf[500000];
char e[10000001];
int s;

void check(int d){
	for(int a=0;(a+=d)<=s;){
		if(!e[a]) return;
	}
	printf("%d",s/d);
	exit(0);
}

main(){
	read(0,rbuf,sizeof rbuf);
	char*r=rbuf;
	int c;

	int n=0;
	while(c=*r++-48,c>=0)n=n*10+c;

	while(n--){
		int a=0;
		while(c=*r++-48,c>=0)a=a*10+c;
		e[s+=a]=1;
	}

	int i;
	for(i=0;++i<=3162;){
		check(i);
	}
	for(i=s/i;;--i){
		check(s/i);
	}
}