#pragma comment(linker, "/STACK:1024000000,1024000000")

#include <cstdio>

#include <string>

#include <cstdlib>

#include <cmath>

#include <iostream>

#include <cstring>

#include <set>

#include <queue>

#include <algorithm>

#include <vector>

#include <map>

#include <cctype>

#include <cmath>

#include <stack>

#define debug() puts("++++");

#define freopenr freopen("in.txt", "r", stdin)

#define freopenw freopen("out.txt", "w", stdout)

using namespace std;

typedef long long LL;

typedef pair<int, int> P;

const int INF = 0x3f3f3f3f;

const double inf = 0x3f3f3f3f3f3f;

const double PI = acos(-1.0);

const double eps = 1e-8;

const int maxn = 1e5 + 5;

const int mod = 1e9 + 7;

const int dr[] = {-1, 1, 0, 0};

const int dc[] = {0, 0, 1, -1};

const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};

int n, m;

const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

inline int Min(int a, int b){ return a < b ? a : b; }

inline int Max(int a, int b){ return a > b ? a : b; }

inline LL Min(LL a, LL b){ return a < b ? a : b; }

inline LL Max(LL a, LL b){ return a > b ? a : b; }

inline bool is_in(int r, int c){

    return r >= 0 && r < n && c >= 0 && c < m;

}

int a[maxn], b[maxn];

int ok[maxn], cnt[maxn];

bool judge(int mid){

    memset(ok, -1, sizeof ok);

    int idx = 0, num = 0;

    for(int i = mid; i > 0; --i){

        if(a[i] && ok[a[i]] == -1)  cnt[++idx] = a[i], ++ok[a[i]], ++num;

        else{

            while(idx && !b[cnt[idx]])  --idx;

            if(!idx)  continue;

            ++ok[cnt[idx]];

            if(ok[cnt[idx]] == b[cnt[idx]]) --idx;

        }

    }

    return num == m && !idx;

}

int solve(){

    int l = m, r = n+1;

    while(l < r){

        int mid = (l + r) >> 1;

        if(judge(mid))  r = mid;

        else l = mid + 1;

    }

    return l == n+1 ? -1 : l;

}

int main(){

    while(scanf("%d %d", &n, &m) == 2){

        for(int i = 1; i <= n; ++i)  scanf("%d", a+i);

        a[n+1] = 0;

        b[0] = -1;

        for(int i = 1; i <= m; ++i)  scanf("%d", b+i);

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

    }

    return 0;

}