C++ :

#include <cstdio>
#include <cstring>
#include <algorithm>

#define DEBUG(args...) fprintf(stderr, args)

#define FOR(i, l, r) for(int i=(l); i<=(r); ++i)
#define REP(i, l, r) for(int i=(l); i< (r); ++i)
#define DFR(i, l, r) for(int i=(l); i>=(r); --i)
#define DRP(i, l, r) for(int i=(l); i> (r); --i)

typedef long long LL;

template<class T>T Min(const T &a, const T &b) {return a < b ? a : b;}
template<class T>T Max(const T &a, const T &b) {return a > b ? a : b;}
template<class T>bool Chkmin(T &a, const T &b) {return a > b ? a=b, 1 : 0;}
template<class T>bool Chkmax(T &a, const T &b) {return a < b ? a=b, 1 : 0;}

namespace FI {
	const int SIZE = 1 << 15 | 1;
	char buf[SIZE], *front, *back;
	void NextChar(char &c) {
		if(front == back) back = (front=buf) + fread(buf, 1, SIZE, stdin);
		c = front==back ? (char)EOF : *front++;
	}
	void NextInt(int &x) {
		char c;
		for(NextChar(c); c>'9'||c<'0'; NextChar(c)) ;
		for(x=0; c>='0'&&c<='9'; NextChar(c)) x = x*10+c-'0';
	}
}

const int SN = 100000 + 47;
const int SK = 1000000 + 47;
const LL INF = 1000000000000LL;

LL a[SK], b[SK], ans;
int w[SN], d[SN], n, m, k;

void Get(int, int *, LL *);
bool Check(LL, int, int *);

int main() {

	int x, y, z;

	FI::NextInt(k), FI::NextInt(n), FI::NextInt(m);
	FOR(i, 1, n) FI::NextInt(w[i]);
	FOR(i, 1, m) FI::NextInt(d[i]);

	Get(n, w, a), Get(m, d, b);

	FOR(i, 1, k) Chkmax(ans, a[i]+b[k-i+1]);

	printf("%lld\n", ans);

	return 0;

}

void Get(int x, int *a, LL *p) {
	LL l = 1, r = INF, mid;
	while(l+1 < r)
		if(Check(mid=l+r>>1, x, a)) r = mid;
		else l = mid;
	l = Check(l, x, a) ? l : l+1;
	int t = 0;
	FOR(i, 1, x) for(LL j=a[i]; j<=l; j+=a[i]) p[++t] = j;
	std::sort(p+1, p+t+1);
}

bool Check(LL x, int y, int *a) {
	LL t = 0;
	FOR(i, 1, y) t += x/a[i];
	return t >= k;
}