#define  _CRT_SECURE_NO_WARNINGS

#include<cstdio>

#include<algorithm>

#include<iostream>

#include<string>

#include<string.h>

using namespace std;

typedef long long ll;

const int maxn = 2e5 + ;

char s1[maxn],s2[maxn];

int del[maxn];

int a[maxn];

int main() {

    scanf("%s", s1);

    scanf("%s", s2);

    int len = strlen(s1);

    int len2 = strlen(s2);

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

        scanf("%d", &a[i]);

    int l = , r = len-;//二分删掉的数

    while (l <= r) {

        memset(del, -, sizeof(del));

        int mid = l + r >> ;

        int ok = ;

        for (int i = ; i < mid; i++) del[a[i]-] = ;

        int i = ,j = ;

        while (i < len&&j < len2)

        {

            if (del[i] == ) { i++; continue; }

            if (s1[i] == s2[j])i++, j++;

            else i++;

            if (j == len2)break;

        }

        if (j == len2) {l = mid + ; }

        else r = mid- ;

    }

    cout << l-;

}