#include <bits/stdc++.h>
// v.erase( unique(all(v)) , v.end() ) -----> removes duplicates and resizes the vector as so
using namespace std;
#define ll long long
#define lld long double
const lld pi = 3.14159265358979323846;
#define pb push_back
#define pf push_front
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define getunique(v) {sort(v.begin(), v.end()); v.erase(unique(v.begin(), v.end()), v.end());}
constexpr int mod = (int)(1e9+7);
#define log(x) (31^__builtin_clz(x)) // Easily calculate log2 on GNU G++ compilers
int main()
{ios_base::sync_with_stdio(0),cin.tie(0);
string t,p;cin>>t>>p;
int n=t.size(); int m=p.size(); int a[n+1];
for(int i=1;i<=n;i++){
cin>>a[i];
}
int en=n,st=0;int ans=0;
while(en>=st){
int mid=en-(en-st)/2;
bool blocked[n+1]={};
for(int i=1;i<=mid;i++){
blocked[a[i]-1]=1;
}
int cur=0;
for(int i=0;i<n;i++){
if(blocked[i])continue;
if(cur==m)break;
if(t[i]==p[cur])cur++;
}
if(cur==m){
ans=mid;
st=mid+1;continue;
}
en=mid-1;
}
cout<<ans<<'\n';
return 0;
}
/*
*/
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