#include <bits/stdc++.h>
using namespace std;
int main() {
int t,c=0;
cin >> t;
int b = t;
vector<int> v;
while(t--)
{
int n;
cin >> n;
v.push_back(n);
}
for(int i=0;i<b-1;i++)
{
if(v[i]==v[i+1])
{
c++;
}
}
cout << c << endl;
if(c == b-1)
{
cout << "YES" << endl;
}
else
{
cout << "NO" << endl;
}
return 0;
}
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