#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define ld long double

using namespace std;

string s;
string t;

bool can(vector<ll>v, ll m) {
    set<ll>ss(v.begin()+m+1, v.end());
    string n;
    for (auto i:ss) {
        n.push_back(s[i-1]);
    }
    ll j=0;
    for (auto i:n) {
        if (i==t[j]) j++;
        if (j==t.size()) return true;
    }
    return false;
}

int main() {
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    cin >> s >> t;
    ll n=s.size();
    vector<ll>v(n);
    for (auto &i:v) cin >> i;
    ll l=0, r=n-1, m;
    while (l<=r) {
        m = (l + r) / 2;
        if (can(v, m)) {
            if (m==n-1 || !can(v,m+1)) {
                cout << m+1 << endl;
                return 0;
            }
            else l=m+1;
        }
        else r=m-1;
    }
    cout << 0 << endl;
    return 0;
}