蒟蒻求助！

#include<bits/stdc++.h>
using namespace std;
int a[110];
int main()
{
    int n,x;
    cin>>n;
    bool pd;
    for(int i=1;i<=n;i++)
    {
        cin>>x;
        if(x!=a[i-1])pd=true,a[i]=x;
    }
    if(!pd){cout<<"NO"<<endl;return 0;}
    sort(a+1,a+1+n);
    cout<<a[n-1]<<endl;
}