1 #include<cstdio>
2 int n,a[100007];
3 int main(){
4 scanf("%d",&n);
5 for(int i=1;i<=n;++i)scanf("%d",a+i);
6 int L=1,R=n;
7 while(L<n&&a[L]<a[L+1])++L;
8 while(R>1&&a[R]<a[R-1])--R;
9 for(int i=L+1;i<=R;++i)if(a[L]!=a[i])return puts("NO"),0;
10 return puts("YES"),0;
11 }
1 #include <iostream>
2 using namespace std;
3 int N;
4 int V[105];
5 int main()
6 {
7 cin>>N;
8 for(int i=1;i<=N;i++)cin>>V[i];
9 int i=1;
10 while(i<N&&V[i]<V[i+1])i++;
11 while(i<N&&V[i]==V[i+1])i++;
12 while(i<N&&V[i]>V[i+1])i++;
13 if(i<N)cout<<"NO";
14 else cout<<"YES";
15 return 0;
16 }
1 #include<iostream>
2 #include<cstdio>
3 using namespace std;
4 int n;
5 int a[1001];
6 int main()
7 {
8 scanf("%d",&n);
9 for(int i=1;i<=n;i++)scanf("%d",a+i);
10 int i=1;
11 while(i+1<=n && a[i+1]>a[i])i++;
12 while(i+1<=n && a[i+1]==a[i])i++;
13 while(i+1<=n && a[i+1]<a[i])i++;
14 if(i<n)printf("NO");else printf("YES");
15 return 0;
16 }
1 #include<bits/stdc++.h>
2 using namespace std;
3
4 int main()
5 {
6 int n;
7 cin>>n;
8 int arr[n];
9 for(int i=0;i<n;i++)
10 cin>>arr[i];
11 int i=0;
12 while(arr[i+1]>arr[i] && i+1<n)
13 i++;
14 while(arr[i]==arr[i+1] && i+1<n)
15 i++;
16 while(arr[i]>arr[i+1] && i+1<n)
17 i++;
18 if(i==n-1)
19 cout<<"YES";
20 else cout<<"NO";
21
22
23 }
1 #include <bits/stdc++.h>
2
3 using namespace std;
4
5 int a[102];
6 int n;
7 void sol(string s) {
8 cout << s;
9 exit(0);
10 }
11 int main() {
12 #ifndef ONLINE_JUDGE
13 freopen("CF.in", "r", stdin);
14 #endif
15 cin >> n;
16 for (int i = 1; i <= n; ++i)cin >> a[i];
17 int i=1;
18 while(i+1<=n&&a[i]<a[i+1])++i;
19 while(i+1<=n&&a[i]==a[i+1])++i;
20 while(i+1<=n)
21 {
22 if(a[i]<=a[i+1])sol("NO");
23 ++i;
24 }sol("YES");
25 }
