#include<stdio.h>
#define N 300001
#define DEFINE_LEFTIST(type, M, is_persistent) \
int hl_##type[M]; \
int hr_##type[M]; \
int hh_##type[M]; \
type ha_##type[M]; \
int halc_##type; \
int leftist_##type(type x) { int p = ++halc_##type; ha_##type[p]=x; hh_##type[p] = 1; hl_##type[p]=hr_##type[p]=0; return p; } \
int leftist_##type##_copy(int q) {\
if(!is_persistent)return q; \
if(!q)return 0;\
int p=++halc_##type; \
hl_##type[p]=hl_##type[q]; \
hr_##type[p]=hr_##type[q]; \
hh_##type[p]=hh_##type[q]; \
ha_##type[p]=ha_##type[q]; \
return p; \
} \
int leftist_##type##_merge(int l,int r) \
{ \
if(!l||!r) { return leftist_##type##_copy(l^r); } \
if(lt_##type(ha_##type[r],ha_##type[l])) return leftist_##type##_merge(r,l); \
l=leftist_##type##_copy(l); \
hr_##type[l]=leftist_##type##_merge(hr_##type[l],r); \
if(hh_##type[hr_##type[l]] > hh_##type[hl_##type[l]]) { int temp = hr_##type[l]; hr_##type[l] = hl_##type[l], hl_##type[l] = temp; } \
hh_##type[l] = hh_##type[hr_##type[l]] + 1; \
return l; \
} \
int leftist_##type##_push(int v,type x) { return leftist_##type##_merge(v, leftist_##type(x)); } \
type leftist_##type##_top(int v) { return ha_##type[v]; } \
int leftist_##type##_pop(int v) { return leftist_##type##_merge(hl_##type[v], hr_##type[v]); }
typedef long long i64;
int lt_i64(i64 a, i64 b){return a>b;}
DEFINE_LEFTIST(i64, 2000000, 0);
int n,M;
int e[N][3],eo,h[N],pq[N];
long long m[N],c[N];
void link(int u,int v,int w) { e[++eo][0]=v,e[eo][1]=w,e[eo][2]=h[u],h[u]=eo; }
void dfs(int u,int p,int ci)
{
m[u]=c[u]=0;
if(u > n)
{
pq[u]=leftist_i64_push(pq[u],ci);
pq[u]=leftist_i64_push(pq[u],ci);
m[u]=1;
c[u]=-ci;
return;
}
for(int v,j=h[u];j;j=e[j][2])if((v=e[j][0])-p)
{
dfs(v,u,e[j][1]);
pq[u]=leftist_i64_merge(pq[u],pq[v]);
m[u]+=m[v];
c[u]+=c[v];
}
if(u!=1)
{
while(m[u]>1)
{
--m[u];
c[u]+=leftist_i64_top(pq[u]);
pq[u]=leftist_i64_pop(pq[u]);
}
long long x=leftist_i64_top(pq[u]);
pq[u]=leftist_i64_pop(pq[u]);
long long x2=leftist_i64_top(pq[u]);
pq[u]=leftist_i64_pop(pq[u]);
pq[u]=leftist_i64_push(pq[u],x+ci);
pq[u]=leftist_i64_push(pq[u],x2+ci);
c[u]-=ci;
}
else
{
while(m[1]>0)
{
--m[1];
c[1]+=leftist_i64_top(pq[1]);
pq[1]=leftist_i64_pop(pq[1]);
}
printf("%lld",c[1]);
}
}
int main()
{
scanf("%d%d",&n,&M);
for(int p,c,i=2;i<=n+M;++i) scanf("%d%d",&p,&c),link(p,i,c);
dfs(1,1,-1);
}
