#include <algorithm>
#include <cstring>
using namespace std;
int dp[2][5555];
int main()
{
char s1[5555],s2[5555];
s1[0]=s2[0]=':';
int n;
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>s1;
s2=s1;
}
reverse(s2+1,s2+1+n);
// cout<<s2;
memset(dp,0,sizeof(dp));
for(int i=1;i<=n;i++)
for(int j=1;j<=n;j++)
{
if(s1==s2[j])
dp[i%2][j]=dp[(i-1)%2][j-1]+1;
else
dp[i%2][j]=max(dp[(i-1)%2][j],dp[i%2][j-1]);
}
cout<<n-dp[n%2][n]<<endl;
return 0;
}