#include<stdio.h>
#include<set>
#include<algorithm>
using namespace std;
struct xy { long long g, type, w; }G[52252];
bool sort_g(xy a, xy b) {return a.g > b.g;}
int a[25252], b[25252];
set<int>L[2], R[2];
long long cnt[2], ln;
int main() {
int i, j;
long long A, B, n, m;
scanf("%lld%lld%lld%lld", &A, &B, &n, &m);
long long ans = B*n + A*m;
for (i = 1; i <= n; i++)scanf("%d", &a[i]);
for (i = 1; i <= m; i++)scanf("%d", &b[i]);
sort(a + 1, a + n + 1), sort(b + 1, b + m + 1);
a[n + 1] = A, b[m + 1] = B;
cnt[0] = m, cnt[1] = n;
for (i = 0; i < n + 1; i++)G[ln++] = { a[i + 1] - a[i],0,i };
for (i = 0; i < m + 1; i++)G[ln++] = { b[i + 1] - b[i],1,i };
sort(G, G + ln, sort_g);
long long ccnt = 0;
for (i = 0; i < ln; i++) {
long long g = G[i].g, type = G[i].type, w = G[i].w;
bool fa = L[type].find(i + 1) != L[type].end();
bool fb = R[type].find(i) != R[type].end();
if (fa&&fb)L[type].erase(i + 1), R[type].erase(i);
else if (fa)L[type].erase(i + 1), L[type].insert(i),cnt[!type]--;
else if (fb)R[type].erase(i), R[type].insert(i + 1), cnt[!type]--;
else L[type].insert(i), R[type].insert(i + 1), cnt[!type]--;
ans -= g*cnt[type];
ccnt += cnt[type];
if (ccnt == n*m)break;
}
printf("%lld", ans);
return 0;
}
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