#include <bits/stdc++.h>
using namespace std;
#define int              long long int
#define double           long double
#define print(a)         for(auto x : a) cout << x << " "; cout << endl
inline int power(int a, int b) {
    int x = 1;
    while (b) {
        if (b & 1) x *= a;
        a *= a;
        b >>= 1;
    }
    return x;
}


const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;

//_ ***************************** START Below *******************************

vector<int> a;
vector<int> b;

int consistency(int n, int m){
	int ans = 0;
	
	int i = 0, j = 0;
	while(i<n && j<m){
		while(i<n && a[i] < b[j]) i++;
		if(i==n) break;
		
		while(j<m && b[j] < a[i]) j++;
		if(j==m) break;
		
		if(a[i] != b[j]) continue;
		
		int p = i+1;
		while(p<n && a[p] == a[i]) p++;
		
		int q = j+1;
		while(q<m && b[q] == b[j]) q++;
		
		ans += (p-i)*(q-j);
		
		i = p;
		j = q;
	}
	
	return ans;
}	








int practice(int n, int m){
	
	return 0;
}


void solve() {
    
    int n, m;
    cin>>n >> m;
    
    a.resize(n);
    b.resize(m);
    for(int i=0; i<n; i++) cin >> a[i];
    for(int i=0; i<m; i++) cin >> b[i];
    
    cout << consistency(n, m) << endl;


}





int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int t = 1;
    while (t--) {
        solve();
    }

    return 0;
}