#include <bits/stdc++.h>
using namespace std;
const int mxn = 2 * 100000 + 6;
int n, root;
int a[mxn];
int c[mxn];
int s[mxn];
int base;
int ans = 0x3f3f3f3f;
int main() {
  cin >> n >> root;
  for (int i = 1; i <= n; ++i) {
    scanf("%d", &a[i]);
    if (i == root && a[i] != 0) {
      ++base;
      a[i] = 0;
    }
    ++c[a[i]];
  }
  partial_sum(c, c + n, s);
  int c0 = 0;
  for (int i = 0; i < n; ++i) {
    c0 += (c[i] == 0);
    int mov = c[0] - 1 + n - s[i];
    int sum = max(mov, c0);
    if (i || n == 1) {
      ans = min(ans, sum);
    }
  }
  cout << ans + base << endl;
  return 0;
}
