#include <stdio.h>
int main(void){
    int a[100000],i,ans,n,point;
    scanf("%d",&n);
    ans=n-1;
    for(i=0;i<n;i++){
        scanf("%d",&a[i]);
        if(a[i]==n){
            point=i;
        }
    }
    for(i=point-1;i>=0;i--){
        if(a[i]==ans){
            ans-=1;
            
        }
    }
    printf("%d",ans);
}