#include <stdio.h>
#include <stdlib.h>
int main(){
  int N,*a;
  int i,result;
  scanf("%d",&N);
  a = (int*)malloc(sizeof(int)*N);
  for(i=0;i<N;i++){
    scanf("%d",&a[i]);
  }
  result = N;
  for(i=N-1;i>=0;i--){
    if(a[i]==result) result--;
  }

  printf("%d\n",result);
  return 0;
}