int main()
{
	char dna1[500],dna2[500];
	double a;
	int t=0,i,flag=0;
	int len1,len2;
	double b;
	scanf("%lf",&a);
	scanf("%s",dna1);
	scanf("%s",dna2);
	len1=strlen(dna1);
	len2=strlen(dna2);
	if(len1==len2)
	{
		for(i=0;i<len1;i++)
		{
			if((dna1[i]=='A'||dna1[i]=='T'||dna1[i]=='G'||dna1[i]=='C')&&(dna2[i]=='A'||dna2[i]=='T'||dna2[i]=='G'||dna2[i]=='C'))
			{
		     	if(dna1[i]==dna2[i]) t++;
			    if(dna1[i]!=dna2[i]) continue;
			}
            if((dna1[i]!='A'&&dna1[i]!='T'&&dna1[i]!='G'&&dna1[i]!='C')||(dna2[i]!='A'&&dna2[i]!='T'&&dna2[i]!='G'&&dna2[i]!='C'))
			 {
				 flag=1;
				 break;
			 }
		}
		if(flag==0)
		{
		     b=(double)t/len1;
		     if(b>a) printf("yes");
		     if(b<=a) printf("no");
		}
	}
	if(len1!=len2) printf("error");
	if(flag==1) printf("error");
	return 0;
}
