#include<bits/stdc++.h>
using namespace std;
int n,a[1000001],b[1000001];
int main(){
    scanf("%d",&n);
    for(int i =1;i<=n;i++){
        scanf("%d%d",&a[i-1],&b[i-1]);
    }
    int x = 0,y = 1;
    
    for(int i = 0;i<=n-1;i++){
        if(a[i]!=b[i]) x++;
        if(a[i]!=b[n-1-i]) y++;
    }
    
    printf("%d",min(x,y));
}