#include <iostream>
#include <cassert>
#include <queue>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <ctime>
#include <map>
#include <set>
using namespace std;
#define int long long
#define pii pair<int, int>
#define eb emplace_back
#define F first
#define S second
#define test(x) cout << "Test: " << x << '\n'
#define lowbit(x) (x & -x)
#define debug puts("qwq");
#define open(x) freopen(#x".in", "r", stdin);freopen(#x".out", "w", stdout);
#define close fclose(stdin);fclose(stdout);
namespace FastIO {
template <typename T = int>
inline T read() {
T s = 0, w = 1;
char c = getchar();
while (!isdigit(c)) {
if (c == '-') w = -1;
c = getchar();
}
while (isdigit(c)) s = (s << 1) + (s << 3) + (c ^ 48), c = getchar();
return s * w;
}
template <typename T>
inline void read(T &s) {
s = 0;
int w = 1;
char c = getchar();
while (!isdigit(c)) {
if (c == '-') w = -1;
c = getchar();
}
while (isdigit(c)) s = (s << 1) + (s << 3) + (c ^ 48), c = getchar();
s = s * w;
}
template <typename T, typename... Arp> inline void read(T &x, Arp &...arp) {
read(x), read(arp...);
}
template <typename T>
inline void write(T x, char ch) {
if (x < 0) x = -x, putchar('-');
static char stk[25];
int top = 0;
do {
stk[top++] = x % 10 + '0', x /= 10;
} while (x);
while (top) putchar(stk[--top]);
putchar(ch);
return;
}
template <typename T>
inline void smax(T &x, T y) {
if (x < y) x = y;
}
template <typename T>
inline void smin(T &x, T y) {
if (x > y) x = y;
}
void quit() {
exit(0);
}
} using namespace FastIO;
const int N = 1e6 + 19;
int f[N], w[N], d[N], root[N];
struct LeftTree {
int val[N], t[N], ls[N], rs[N], cnt;
int build_new(int v) {
val[++cnt] = v;
return cnt;
}
int merge(int p, int q) {
if (!p || !q) return p + q;
if (val[p] < val[q]) swap(p, q);
rs[p] = merge(rs[p], q);
if (t[ls[p]] < t[rs[p]]) swap(ls[p], rs[p]);
t[p] = t[rs[p]] + 1;
return p;
}
void del(int &p) {
p = merge(ls[p], rs[p]);
}
} tr;
signed main() {
int n, m, ans = 0;
read(n, m);
for (int i = 2; i <= n + m; ++i) {
read(f[i], w[i]);
ans += w[i];
d[f[i]]++;
}
for (int u = n + m; u >= 2; --u) {
if (u <= n) while (--d[u]) tr.del(root[u]);
int R = tr.val[root[u]]; tr.del(root[u]);
int L = tr.val[root[u]]; tr.del(root[u]);
root[u] = tr.merge(root[u], tr.merge(tr.build_new(L + w[u]), tr.build_new(R + w[u])));
root[f[u]] = tr.merge(root[f[u]], root[u]);
}
while (d[1]--) tr.del(root[1]);
while (root[1]) ans -= tr.val[root[1]], tr.del(root[1]);
write(ans, '\n');
return 0;
}
