#include<stdio.h>
#include<vector>
#include<algorithm>
using namespace std;
struct maxs{
	int mi,m;
};
vector<int> v;
maxs vm;
int main(){
	freopen("secv.in","r",stdin);
	freopen("secv.out","w",stdout);
	int n,last;
	vm.m=1;
	vm.mi=1;
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		int x;
		scanf("%d",&x);
		v.push_back(x);
	}
	for(int i=1;i<=n;i++){
		last=1;
		for(int j=i;j<=n;j++){
			if(v[j]==last){
				++last;
				if(last>vm.m){
					vm.m=last;
					vm.mi=j-i+1;
				}
			}
		}
	}
	printf("%d\n",vm.mi);
	return 0;
}