#include <string>
#include <vector>

class Solution {
public:
    int minDeletionSize(std::vector<std::string>& strs) {
        int ans = 0;
        for(int i = 0;i<strs[0].size();i++){
            for (int j = 1; j < strs.size(); j++) {
                if (strs[j][i] < strs[j-1][i]) {
                    ans++;
                    break;
                }
            }
        }
        return ans;
    }
};