#include <bits/stdc++.h>
#define ll long long
#define itn int
#define ms(x,y) memset(x,y,sizeof(x))
#define f first
#define s second
#define pb push_back
#define pob pop_back
#define nl "\n" ;
#define sp setprecision
using namespace std ;
const ll BIG = 1e7 ;
string s ;
multiset < ll > cars ;
priority_queue < ll > bags ;
ll cnt , c , n ;
int main()
{
cin>>n>>c;
for ( int i = 0 ; i<n ; i++ )
{
ll x ;
cin>>x;
bags.push(x);
}
for ( int i = 0 ; i<c ; i++ )
{
ll x ;
cin>>x;
cars.insert(x);
}
while ( 1 )
{
for ( multiset <ll > :: reverse_iterator it = cars.rbegin() ; it != cars.rend() ; it++ )
{
if ( *it >= bags.top() )
{
bags.pop() ;
if ( bags.empty() )
{
cout<<++cnt;
return 0 ;
}
}
else
{
break;
}
}
if ( !bags.empty())
cnt++;
cnt++;
}
}
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