int main(){
	double p;
	int la,i,y=0,lb,s=0;
	char zfa[501],zfb[501];
	scanf("%lf",&p);
	scanf("%s",zfa);
	scanf("%s",zfb);
	la=strlen(zfa);
	lb=strlen(zfb);
	if(la!=lb){
       y=1;
	}
	if(y==0){
	for(i=0;zfa[i]!='\0'&&zfb[i]!='\0';i++){
		if(((zfa[i]!='A')&&(zfa[i]!='T')&&(zfa[i]!='C')&&(zfa[i]!='G'))||((zfb[i]!='A')&&(zfb[i]!='T')&&(zfb[i]!='C')&&(zfb[i]!='G'))){
			y=1;
			break;
	   
		}
		if(zfa[i]==zfb[i]){
		s++;
		}
	}
	if((1.0*s/la)>p&&y==0){
	printf("yes");
	}
	else if(y==0){
	printf("no");
	}
	}
	if(y==1){
 printf("error");
	
	}



	return 0;
	

	






}