Language: C++

                #include <bits/stdc++.h>
                                        #include<iostream>
                                        #include<cstdio>
                                        #include<vector>
                                        #include<queue>
                                        #include<map>
                                        #include<cstring>
                                        #include<string>
                                        #include <math.h>
                                        #include<algorithm>
                                    //    #include <boost/multiprecision/cpp_int.hpp>
                                        #include<functional>
                               #define int long long
                                        #define inf  1000000007
                                        #define pa pair<int,int>
                                        #define ll long long
                                        #define pal pair<double,pa>
                                        #define ppap pair<pa,int>
                                        #define ppa pair<int,pa>
                                        #define ssa pair<string,int>
                                        #define  mp make_pair
                                        #define  pb push_back
                                        #define EPS (1e-10)
                                        #define equals(a,b) (fabs((a)-(b))<EPS)
                                 
                                        using namespace std;
                               class pas{
                                        	public:
                                        	int x,y;
                                        	pas(int x=0,int y=0):x(x),y(y) {}
                                        	pas operator + (pas p) {return pas(x+p.x,y+p.y);}
                                        	pas operator - (pas p) {return pas(x-p.x,y-p.y);}
                                        	pas operator * (int a) {return pas(x*a,y*a);}
                                        	pas operator / (int a) {return pas(x/a,y/a);}
                                        	
                                        	bool operator < (const pas &p) const{
                                        		return x != p.x ? x<p.x: y<p.y;
                                        	}
                                        	bool operator == (const pas &p) const{
                                        		return abs(x-p.x)==0 && abs(y-p.y)==0;
                                        	}
                                        };
                                        class Point{
                                        	public:
                                        	double x,y;
                                        	Point(double x=0,double y=0):x(x),y(y) {}
                                        	Point operator + (Point p) {return Point(x+p.x,y+p.y);}
                                        	Point operator - (Point p) {return Point(x-p.x,y-p.y);}
                                        	Point operator * (double a) {return Point(x*a,y*a);}
                                        	Point operator / (double a) {return Point(x/a,y/a);}
                                        	double absv() {return sqrt(norm());}
                                        	double norm() {return x*x+y*y;}
                                        	bool operator < (const Point &p) const{
                                        		return x != p.x ? x<p.x: y<p.y;
                                        	}
                                        	bool operator == (const Point &p) const{
                                        		return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
                                        	}
                                        };
                                        typedef Point Vector;
                                 
                                        struct Segment{
                                        Point p1,p2;
                                        };
                                         double dot(Vector a,Vector b){
                                        	return a.x*b.x+a.y*b.y;
                                        }
                                        double cross(Vector a,Vector b){
                                        	return a.x*b.y-a.y*b.x;
                                        }
                                    
            bool parareru(Point a,Point b,Point c,Point d){
            //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
            	return abs(cross(a-b,d-c))<EPS;
            }
            double distance_ls_p(Point a, Point b, Point c) {
              if ( dot(b-a, c-a) < EPS ) return (c-a).absv();
              if ( dot(a-b, c-b) < EPS ) return (c-b).absv();
              return abs(cross(b-a, c-a)) / (b-a).absv();
            }
            bool is_intersected_ls(Segment a,Segment b) {
            	if(a.p1==b.p1||a.p2==b.p1||a.p1==b.p2||a.p2==b.p2) return false;
            	if(parareru((a.p2),(a.p1),(a.p1),(b.p2))&&parareru((a.p2),(a.p1),(a.p1),(b.p1))){
            //		cout<<"sss"<<endl;
            		if(dot(a.p1-b.p1,a.p1-b.p2)<EPS) return true;
            		if(dot(a.p2-b.p1,a.p2-b.p2)<EPS) return true;
            		if(dot(a.p1-b.p1,a.p2-b.p1)<EPS) return true;
            		if(dot(a.p1-b.p2,a.p2-b.p2)<EPS) return true;
            		return false;
            	}
              else return ( cross(a.p2-a.p1, b.p1-a.p1) * cross(a.p2-a.p1, b.p2-a.p1) < EPS ) && ( cross(b.p2-b.p1, a.p1-b.p1) * cross(b.p2-b.p1, a.p2-b.p1) < EPS );
            }
             
            double segment_dis(Segment a,Segment b){
            	if(is_intersected_ls(a,b))return 0;
            	double r=distance_ls_p(a.p1, a.p2, b.p1);
            	r=min(r,distance_ls_p(a.p1, a.p2, b.p2));
            	r=min(r,distance_ls_p(b.p1, b.p2, a.p2));
            	r=min(r,distance_ls_p(b.p1, b.p2, a.p1));
            	return r;
            }
            Point intersection_ls(Segment a, Segment b) {
              Point ba = b.p2-b.p1;
              double d1 = abs(cross(ba, a.p1-b.p1));
              double d2 = abs(cross(ba, a.p2-b.p1));
              double t = d1 / (d1 + d2);
             
              return a.p1 + (a.p2-a.p1) * t;
            }
             
                            string itos( int i ) {
                            ostringstream s ;
                            s << i ;
                            return s.str() ;
                            }
                             
                            int gcd(int v,int b){
                            	if(v>b) return gcd(b,v);
                            	if(v==b) return b;
                            	if(b%v==0) return v;
                            	return gcd(v,b%v);
                            }
             
                            double distans(double x1,double y1,double x2,double y2){
                            	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                            	return sqrt(rr);
                            	
                            }
                            
            int pr[2000010];
            int inv[2000010];
            
            int beki(int wa,int rr,int warukazu){
            	if(rr==0) return 1ll;
            	if(rr==1) return wa%warukazu;
            	if(rr%2==1) return (beki(wa,rr-1,warukazu)*wa)%warukazu;
            	int zx=beki(wa,rr/2,warukazu);
            	return (zx*zx)%warukazu;
            }
              
            void gya(){
            	pr[0]=1;
            	for(int i=1;i<2000010;i++){
            		pr[i]=(pr[i-1]*i)%inf;
            	}
            	for(int i=0;i<2000010;i++) inv[i]=beki(pr[i],inf-2,inf);
            	
            }
             
            
             //sort(ve.begin(),ve.end(),greater<int>());
                                     //----------------kokomade tenpure------------
            //vector<double> ans(100000000),ans2(100000000);
            
           
int par[200100],ranks[200100],kosuu[200100];     

void shoki(int n){
	for(int i=0;i<n;i++){
		par[i]=i;
		ranks[i]=0;
		kosuu[i]=1;
	}
}

int root(int x){
	return par[x]==x ? x : par[x]=root(par[x]);
}

bool same(int x,int y){
return root(x)==root(y);
}

void unite(int x,int y){
 x=root(x);
 y=root(y);
	int xx=kosuu[x],yy=kosuu[y];
 if(x==y) return;
	if(ranks[x]<ranks[y]){
		par[x]=y;
		kosuu[y]=yy+xx;
	}
 else {
	par[y]=x;
	if(ranks[x]==ranks[y]) ranks[x]=ranks[x]+1;
 	kosuu[x]=yy+xx;
 }
	return;
}
vector<int> G2[1030];
vector<int> G[1030];
int n;
int a[1020];
int dp[2][10001];
pas df[1002];
pas saiki(int u){
		if(df[u]!={-1,-1}) return df[u];
	if(G[u].size()==0){
		df[u]={a[u],0};
		return {a[u],0};
	}
	
	for(int i=0;i<10001;i++)dp[0][i]=0,dp[1][i]=0;
	dp[0][0]=1;
	int cn=0;
	int sum=0;
	int mi=0;
	for(auto v:G[u]){
		pas w=saiki(v);
		mi+=min(w.x+w.y);
		if(mi>a[u]){
				cout<<"IMPOSSIBLE"<<endl;
			exit(1);
		}
	}
	
	for(auto v:G[u]){
		pas w=saiki(v);
		cn^=1;
		if(min(w.x,w.y)>a[u]){
				cout<<"IMPOSSIBLE"<<endl;
			exit(1);
		}
		sum+=w.x+w.y;
		for(int i=0;i<10001;i++)dp[cn][i]=0;
		for(int i=5000;i>=0;i--){
			
			if(i-w.x>=0)dp[cn][i]+=dp[1^cn][i-w.x];
			if(i-w.y>=0)dp[cn][i]+=dp[1^cn][i-w.y];
		}
		
	}
	int k;
	for( k=a[u];k>=0;k--){
		if(dp[cn][k]) break;
		if(k==0){
			cout<<"IMPOSSIBLE"<<endl;
			exit(1);
		}
	}
	df[u]={a[u],sum-k};
	return {a[u],sum-k};
}
      signed main(){
  cin>>n;
      	for(int i=1;i<=n;i++)df[u]={-1,-1};
      	for(int i=2;i<=n;i++){
      		int yy;
      		cin>>yy;
      		G[yy].pb(i);
      	}
      	for(int i=1;i<=n;i++)cin>>a[i];
      	
      
      	saiki(1);
      	
      	cout<<"POSSIBLE"<<endl;
      	
        	return 0;
        }


Compiler output:
a.cc: In function 'pas saiki(long long int)':
a.cc:197:27: error: expected primary-expression before '{' token
  197 |                 if(df[u]!={-1,-1}) return df[u];
      |                           ^
a.cc:197:27: error: expected ')' before '{' token
  197 |                 if(df[u]!={-1,-1}) return df[u];
      |                   ~       ^
      |                           )
a.cc:210:24: error: no matching function for call to 'min(long long int)'
  210 |                 mi+=min(w.x+w.y);
      |                     ~~~^~~~~~~~~
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:233:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::min(const _Tp&, const _Tp&)'
  233 |     min(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:233:5: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_algobase.h:281:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::min(const _Tp&, const _Tp&, _Compare)'
  281 |     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:281:5: note:   candidate expects 3 arguments, 1 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5686:5: note: candidate: 'template<class _Tp> constexpr _Tp std::min(initializer_list<_Tp>)'
 5686 |     min(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5686:5: note:   template argument deduction/substitution failed:
a.cc:210:24: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
  210 |                 mi+=min(w.x+w.y);
      |                     ~~~^~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:5696:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::min(initializer_list<_Tp>, _Compare)'
 5696 |     min(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5696:5: note:   candidate expects 2 arguments, 1 provided
a.cc: In function 'int main()':
a.cc:246:33: error: 'u' was not declared in this scope
  246 |         for(int i=1;i<=n;i++)df[u]={-1,-1};
      |                                 ^