#include <bits/stdc++.h>
using namespace std;
namespace my_header {
const int INF = 0x3f3f3f3f;
inline char gchar() {
  char ret = getchar();
  for (; (ret == '\n' || ret == '\r' || ret == ' ') && ret != EOF;
       ret = getchar())
    ;
  return ret;
}
template <class T>
inline void fr(T &ret, char c = ' ', int flg = 1) {
  for (c = getchar(); (c < '0' || '9' < c) && c != '-'; c = getchar())
    ;
  if (c == '-') {
    flg = -1;
    c = getchar();
  }
  for (ret = 0; '0' <= c && c <= '9'; c = getchar()) ret = ret * 10 + c - '0';
  ret = ret * flg;
}
inline int fr() {
  int t;
  fr(t);
  return t;
}
template <class T>
inline void fr(T &a, T &b) {
  fr(a), fr(b);
}
template <class T>
inline void fr(T &a, T &b, T &c) {
  fr(a), fr(b), fr(c);
}
template <class T>
inline char wr(T a, int b = 10, bool p = 1) {
  return a < 0 ? putchar('-'), wr(-a, b, 0)
               : (a == 0 ? (p ? putchar('0') : p)
                         : (wr(a / b, b, 0), putchar('0' + a % b)));
}
template <class T>
inline void wt(T a) {
  wr(a), puts("");
}
template <class T>
inline void wt(T a, T b) {
  wr(a), putchar(' '), wr(b), puts("");
}
template <class T>
inline void wt(T a, T b, T c) {
  wr(a), putchar(' '), wr(b), putchar(' '), wr(c), puts("");
}
template <class T>
inline void wt(T a, T b, T c, T d) {
  wr(a), putchar(' '), wr(b), putchar(' '), wr(c), putchar(' '), wr(d),
      puts("");
}
template <class T>
inline T gcd(T a, T b) {
  return b == 0 ? a : gcd(b, a % b);
}
template <class T>
inline T fpw(T b, T i, T _m, T r = 1) {
  for (; i; i >>= 1, b = b * b % _m)
    if (i & 1) r = r * b % _m;
  return r;
}
};  // namespace my_header
using namespace my_header;
char s[222222], t[222222];
int a[222222], b[222222];
int n, m, d;
bool ok() {
  int j = 1;
  for (int i = 1; i <= m; ++i) {
    bool o = false;
    while (j <= n) {
      if (s[j] == t[i] && b[j] > d) {
        o = true;
        ++j;
        break;
      }
      ++j;
    }
    if (!o) return false;
  }
  return true;
}
int main() {
  scanf("%s\n%s\n", s + 1, t + 1);
  n = strlen(s + 1);
  m = strlen(t + 1);
  for (int i = 1; i <= n; ++i) {
    scanf("%d", a + i);
    b[a[i]] = i;
  }
  int l = 0, r = n;
  while (l < r) {
    d = (l + r + 1) >> 1;
    if (ok()) {
      l = d;
    } else
      r = d - 1;
  }
  d = l + 1;
  while (!ok()) --d;
  wt(d);
  return 0;
}
