#include <bits/stdc++.h>   using namespace std;   const int maxn = 200010;   int a[maxn];   int f[maxn];   int miss[maxn];   int sum[maxn];   int main() {     int n, s;     cin >> n >> s;     for (int i = 1; i <= n; i++) {       scanf( %d , &a[i]);     }     int ans1 = 0;     if (a[s] != 0) {       ans1++;       a[s] = 0;     }     int zero = 0;     for (int i = 1; i <= n; i++) {       f[a[i]]++;       if (a[i] == 0) {         zero++;       }     }     zero--;     int i = 0;     while (zero--) {       while (f[i] != 0) {         i++;       }       f[0]--;       f[i]++;       ans1++;     }     sum[0] = 1;     for (int i = 1; i < n; i++) {       if (f[i] == 0) {         miss[i] = miss[i - 1] + 1;       } else {         miss[i] = miss[i - 1];       }       sum[i] = sum[i - 1] + f[i];     }     int ans2 = 1e9;     for (int i = n - 1; i >= 1; i--) {       int tmp = max((n - sum[i]), miss[i]);       ans2 = min(ans2, tmp);     }     if (n == 1) {       ans2 = 0;     }     cout << ans1 + ans2 << endl;     return 0;   }   