#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
#define len(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define pb push_back
const int MOD = 1e9 + 7;
int mod(int x) {
x %= MOD;
if (x < 0)
x += MOD;
return x;
}
void run() {
int n, m;
cin >> n >> m;
vector<int> v;
for (int i = 1; i < n + m; ++i) {
int p, c;
cin >> p >> c;
--p;
v.pb(c);
}
sort(all(v));
int X = v[len(v) / 2];
int ans = 0;
for (int i = 0; i < len(v); ++i) {
ans += abs(v[i] - X);
}
cout << ans << '\n';
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
run();
}
