killjee_adjacent.cpp

    using namespace std;
    #include<bits/stdc++.h>
     
    int main()
    {
        int n;
        cin>>n;
        int a[n+2];
        a[0] = a[n+1] = 0;
        for(int i = 1; i<=n; i++)
            cin>>a[i];
            
        int ans = 0;
        
        for(int i = 1; i<=n; i+=2)
        {
            if( (a[i] == a[i+1]) || (a[i] == a[i-1]) )
                ans++;
        }
        
        int cnt = 0;
        for(int i = 2; i<=n; i+=2)
        {
            if( (a[i] == a[i+1]) || (a[i] == a[i-1]) )
            {
                cnt++;
            }
        }
        
        
        cout<<min(ans, cnt)<<endl;
            
        return 0;
    }