#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}());
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
double ac;
double TLE() {return (double)(clock() - ac) / CLOCKS_PER_SEC;}
int main(){
ios_base::sync_with_stdio(0),cin.tie(0);
int n;
int m;
cin>>n>>m;
int a[n];
int b[m];
for(int i=0;i<n;i++){
cin>>a[i];
}
for(int i=0;i<m;i++){
cin>>b[i];
}
sort(a,a+n,greater<>());
sort(b,b+n,greater<>());
int c=0;
int j=0;
while(n>m){
n-=2;
c+=2;
}
c+=n;
cout<<c<<endl;
}
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