#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2e5+111;

int n;
ll c1, c2, a[N], b[N];

void work(){
	cin>>n;
	for(int i=0;i<n;i++) cin>>a[i];
	for(int i=1;i<n;i++) if(a[i] <= a[i-1]) {printf("No\n"); return ;}
	printf("Yes\n"); 
}

int main(){
	int t = 1;  //scanf("%d",&t);
	while(t--) work(); return 0;
}