#include<iostream>
#include<string>
using namespace std;
int main(){
    string a,b;
    float x=0,y=0,f;
    cin>>f;
    cin>>a>>b;
    for(int i=0;i<a.size();i++){
        if(a[i]==b[i]){
            x+=1;
        }else{
            y+=1;
        }
    }
    if((max(x,y)/(x+y))>=f){
        cout<<"yes";
    }else{
        cout<<"no";
    }
    return 0;
}