#include<cstdio> #include<iostream> #include<cstring> using namespace std; char a[600]; char b[600]; int main(){ float z; int len,i,s=0; scanf("%f",&z); scanf("%s%s",a,b); len=strlen(a); for(i=0;i<len;i++) if(a[i]==b[i]) s++; if(s*1.0/len>=z) cout<<"yes"; else cout<<"no"; return 0; }