A.cpp

#include <sstream>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <string>
#include <queue>
#include <bitset>
using namespace std;

#define int long long
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
#define REP(i, a) for (int i = 0, _a = (a); i < _a; ++i)
#define REPD(i,n) for(int i = (n)-1; i >= 0; --i)

#define DEBUG(X) { cerr << #X << " = " << (X) << endl; }
#define PR(A, n) { cerr << #A << " = "; FOR(_, 1, n) cerr << A[_] << ' '; cerr << endl; }
#define PR0(A, n) { cerr << #A << " = "; REP(_, n) cerr << A[_] << ' '; cerr << endl; }

#define sqr(x) ((x) * (x))
#define ll long long
#define double long double
typedef pair<int, int> II;
#define PI (2 * acos((double)0))
#define __builtin_popcount __builtin_popcountll
#define SZ(x) ((int)(x).size())
#define ALL(a) (a).begin(), (a).end()
#define MS(a,x) memset(a, x, sizeof(a))
#define next ackjalscjaowjico
#define prev ajcsoua0wucckjsl
#define y1 alkscj9u20cjeijc
#define y0 u9cqu3jioajc

double safe_sqrt(double x) { return sqrt(max((double)0.0, x)); }
int GI(int& x) { return scanf("%lld", &x); }

const int MN = 200111;
int a[MN];
string big, small;
int n;
bool rem[MN];

bool check(int val) {
    memset(rem, 0, sizeof rem);
    FOR(i,1,val) rem[a[i] - 1] = true;

    string s = "";
    REP(i,SZ(big)) if (!rem[i]) s += big[i];

    int i = 0;
    int l = SZ(s);
    if (l < SZ(small)) return false;

    for(char c : small) {
        while (i < l && s[i] != c) ++i;
        if (i == l) return false;

        ++i;
    }
    return true;
}

int32_t main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout << (fixed) << setprecision(9);
    while (cin >> big >> small) {
        n = SZ(big);
        FOR(i,1,n) cin >> a[i];

        int l = 0, r = n, res = 0;
        while (l <= r) {
            int mid = (l + r) >> 1;
            if (check(mid)) {
                res = mid;
                l = mid + 1;
            }
            else r = mid - 1;
        }
        cout << res << endl;
    }
}