小兵的窝

/*
Sample Input
2
1 1
4
1 2 3 2
Sample Output
1
2

Original: IBM Challenge 2004.1
*/
#include <iostream>
using namespace std;
int main()
{
int n;
while (scanf("%d", &n) != EOF) {
register int i, s = 0;
for (i = 1; i <= n; i++) {
  int val;
  scanf("%d", &val);
  s -= val;
  s += i;
}
printf("%u\n", n - s);
}
return 0;
}