#include <bits/stdc++.h>

 using namespace std;

 #define N 200010

 char s[N], p[N];

 int id[N], vis[N], n, m;

 bool check(int x) {

     memset(vis, , sizeof(vis));

     for(int i = ; i <= x; i++) vis[id[i]] = ;

     for(int i = , cnt = ; i <= n; i++) {

         if(vis[i]) continue;

         if(p[cnt] == s[i]) cnt++;

         if(cnt == m + ) return true;

     }

     return false;

 }

 int main() {

     scanf("%s %s", s + , p + );

     n = strlen(s + ), m = strlen(p + );

     for(int i = ; i <= n; i++) scanf("%d", &id[i]);

     int l = , r = n, ans = ;

     while(l <= r) {

         int mid = (l + r) >> ;

         if(check(mid)) {

             ans = mid; l = mid + ;

         } else r = mid - ;

     }

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

     return ;

 }