#include<iostream>
#include<string>
using namespace std;
int main()
{
	string str1,str2;
	double   k;
	cin>>k>>str1>>str2;
	int cnt=0;
	for(int i=0;i<str1.size();i++)
	{
		if(str1[i]==str2[i])
		{
			cnt++;
		}
	}
	if(cnt*1.0/str1.size()>=k)
	{
		cout<<"yes";
	}
	else
	{
		cout<<"no";
	}

	return 0;
 }

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