#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define ar array
/* observation:
with a shit ton of inequalities:
we only go up in the middle if
(Ab-Ac)/(b-c)<(Bx-By)/(x-y)<(Aa-Ab)/(a-b)
*/
//ca compares a's
const int N=1e6+6000;
int A[N],B[N],aa[N],bb[N];
bool ca(int x,int y,int z) {
return (A[x]-A[y])*(x-z)<(A[x]-A[z])*(x-y);
}
bool cb(int x,int y,int z) {
return (B[x]-B[y])*(x-z)<(B[x]-B[z])*(x-y);
}
bool cab(int x,int y,int z,int w) {
return (A[x]-A[y])*(w-z)<(B[z]-B[w])*(y-x);
}
char buf[1<<23],*p1=buf,*p2=buf;
#define getchar() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
inline int rd()
{
int s=0;
char ch=getchar(),last;
while(ch<'0'||ch>'9') last=ch,ch=getchar();
while(ch>='0'&&ch<='9') s=(s<<1)+(s<<3)+(ch^48),ch=getchar();
return last=='-'?-s:s;
}
int num[100];
inline void rt(int x)
{
if(x<0) putchar('-'),x=-x;;
int len=0;
do num[len++]=x%10;while(x/=10);
while(len--) putchar(num[len]+'0');
}
void solve(){
int n=rd(),m=rd();
for(int i=1;i<=n;i++) A[i]=rd();
for(int i=1;i<=m;i++) B[i]=rd();
int ta=0,tb=0;
aa[++ta]=1; bb[++tb]=1;
for(int i=2;i<=n;i++){
while(ta>1 && ca(i,aa[ta],aa[ta-1])) ta--;
aa[++ta]=i;
}
for(int i=2;i<=m;i++){
while(tb>1 && cb(i,bb[tb],bb[tb-1])) tb--;
bb[++tb]=i;
}
int x=1,y=1,ans=0;
while(x<ta || y<tb){
//if already taken all a's force take y
if(x==ta || (y<tb && cab(aa[x],aa[x+1],bb[y],bb[y+1]))){
int cost=(bb[y+1]-bb[y])*A[aa[x]]; y++;
ans+=cost;
}
else{
int cost=(aa[x+1]-aa[x])*B[bb[y]]; x++;
ans+=cost;
}
}
rt(ans);
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
clock_t tStart = clock();
int local=0,multi=0,debug=1,tt=1;
if(local){
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
}
if(multi) cin>>tt;
for(int i=1;i<=tt;i++){
if(debug && multi && local) cout<<"样例 "<<i<<'\n';
solve();
}
fprintf(stderr, "\n>> Runtime: %.10fs\n", (double) (clock() - tStart) / CLOCKS_PER_SEC);
}
