int main(){
double z,r=0;
int m,n,i,error=0;
char a[500],b[500];
scanf("%lf",&z);
scanf("%s\n",a);
scanf("%s",b);
m=strlen(a);
n=strlen(b);
if(m!=n){
error=error+1;
}else{
	for(i=0;a[i];i++){
		if(!(a[i]=='A'||a[i]=='T'||a[i]=='C'||a[i]=='G')){
		error=error+1;
		}else if(!(b[i]=='A'||b[i]=='T'||b[i]=='C'||b[i]=='G')){
		error=error+1;
		}else{
			if(a[i]=='A'&&b[i]=='A'){
			r=r+1;
			}
			if(b[i]=='T'&&a[i]=='T'){
			r=r+1;
			}
			if(a[i]=='G'&&b[i]=='G'){
			r=r+1;
			}
			if(a[i]=='C'&&b[i]=='C'){
			r=r+1;
			}
		}
	}
	r=r/m;
}
if(error!=0){
printf("error");
}else if(r>=z){
printf("yes");
}else{
printf("no");
}
return 0;
}