#![allow(non_snake_case, unused_imports, unused_macros)]
use itertools::{Itertools, iproduct, izip};
use proconio::{fastout, input, marker::Usize1, marker::Chars};

macro_rules! debug {
    ($($a:expr),* $(,)*) => {
        #[cfg(debug_assertions)]
        eprintln!(concat!($("| ", stringify!($a), "={:?} "),*, "|"), $(&$a),*);
    };
}
macro_rules! ndvec {
    ($v:expr; $n:expr) => {
        vec![$v; $n]
    };
    ($v:expr; $n:expr, $($ns:expr),+) => {
        vec![ndvec![$v; $($ns),+]; $n]
    };
}
macro_rules! yes_no {
    ($e:expr) => {
        if $e {
            println!("Yes");
        } else {
            println!("No");
        }
    };
}

#[fastout]
fn main() {
    input! {
        n: usize,
        s: [Chars; n]
    }
    let whites = iproduct!(0..n, 0..n).filter(|&(i, j)| s[i][j] == '#').sorted_unstable().collect_vec();
    let blacks = iproduct!(0..n, n..2 * n).filter(|&(i, j)| s[i][j] == '.').sorted_unstable().collect_vec();


    println!("{}",
        izip!(whites, blacks).map(|(wi, bi)| wi.0.abs_diff(bi.0) + wi.1.abs_diff(bi.1)).sum::<usize>()
    );
}

#[allow(unused)]
fn partition_point<I: num::Integer + Copy>(mut l: I, mut r: I, mut f: impl FnMut(I) -> bool) {
    let one = I::one();
    let two = one + one;
    while l < r {
        let p = (r - l) / two + l;
        if f(p) {
            l = p + one;
        } else {
            r = p;
        }
    }
}