#include<bits/stdc++.h>

 using namespace std;

 const int MAXN=1e5+;

 int N,M,d[MAXN],w[MAXN],cnt[MAXN];

 void read(int &x){

     x=;

     register char c=getchar();

     while(c<||c>)

         c=getchar();

     for(;c>=&&c<=;c=getchar())

         x=(x<<)+(x<<)+c-;

 }

 bool check(int x)

 {

     memset(cnt,,sizeof(cnt));

     int ans = ,val = ;

     for (int i=x; i>=; i--)

         if (d[i]&&++cnt[d[i]]==&&w[d[i]]<i-M+ans+)

         {

             ans++;

             val+=w[d[i]];

         }

    return ans == M && val+M<=x;

 }

 int main()

 {

     read(N),read(M);

     for (int i=; i<=N; i++)

         read(d[i]);

     for (int i=; i<=M; i++)

         read(w[i]);

     int first = ;

     int last = N;

     int mid;

     int best = -;

     while (first <= last)

     {

         mid = (first + last)/;

         if (check(mid))

         {

             last = mid-;

             best = mid;

         }

         else

         {

             first = mid+;

         }

     }

     printf("%d\n",best);

     return ;

 }