UVa 414 - Machined Surfaces

// UVa 414 - Machined Surfaces

#include <iostream>
#include <string>
using namespace std;

int main() {
	int n;
	cin >> n;
	while (n) {
		string st;
		getline(cin, st);
		int mm = 0;
		int m[13];
		for (int i = 0; i < n; i++) {
			getline(cin, st);
			m[i] = 0;
			for (int j = 0; j < st.length(); j++)
				if (st[j] == 'X')
					m[i]++;
			mm = max(mm, m[i]);
		}
		int sol = 0;
		for (int i = 0; i < n; i++)
			sol += mm - m[i];
		cout << sol << endl;
		cin >> n;
	}
	return 0;
}