6

#include<bits/stdc++.h>
using namespace std;
float n;
float a;
string s1;
string s2;
int main()
{
cin>>n;
cin>>s1;
cin>>s2;
for(int i=0;i<s1.size();i++)
{
if(s1[i]==s2[i])
{
a++;
}
}
if(a/s1.size()>n)
{
cout<<"yes"<<endl;
}
else
{
cout<<"no"<<endl;
}
}