int main(){
int biao=0,i,j,n,l,d,c=0,a1=0,a2;
double v,w;
char a[505],b[505];
scanf("%lf",&v);
scanf("%s",a);
scanf("%s",b);
c=strlen(a);
d=strlen(b);
if(c!=d){biao=1;printf("error");}
if(biao==0){for(i=0;i<c;i++){if(!((a[i]=='A'||a[i]=='T'||a[i]=='C'||a[i]=='G')&&(b[i]=='A'||b[i]=='T'||b[i]=='C'||b[i]=='G'))){biao=1;printf("error");break;}}}
if(biao==0){for(i=0;i<c;i++){if(a[i]==b[i])a1++;}w=1.0*a1/c*1.0;if(w>=v)printf("yes");else printf("no");}
return 0;
}