#define qq w##h##i##l##e
#define ab i##f
#define wow e##l##s##e
#define ok b##r##e##a##k
#define nook c##o##n##t##i##n##u##e
#define line i##n##l##i##n##e
#define oo v##o##i##d
#define dd i##n##t
#define word c##h##a##r
#define o r##e##t##u##r##n
#define ooo f##o##r
#define words s##t##r##i##n##g
#define can s##c##a##n##f
#import <ios>
#import <cctype>
line oo write(dd x) {
ab(x>9) write(x*0.1);
wow putchar_unlocked(45), x*=(-1), write(x);
putchar_unlocked(x%10+'0');
}
dd Input() {
word cha;
dd x = 0,d=1;
qq((cha = getchar_unlocked()))
ab((cha != ' ' && cha != '\n' )|| cha == EOF) ok;
ab(cha == EOF) o -32768;
ab(cha=='-')d=-d;
wow
x = cha-48;
qq((cha = getchar_unlocked())) {
ab(cha == ' ' || cha == '\n') ok;
x = x*10 + cha-48;
}
o x*d;
}
dd main() {
word a[1000];
qq (can("%s", a)!=EOF) {
dd b[26]={0}, alb, ans=0, c=0;
ooo (dd i=0;i<1000;i++) {
ab (islower(a[i])) b[a[i]-97]++;
wow ab (isupper(a[i])) b[a[i]-65]++;
wow ab (a[i]=='\0') {
alb=i;
ok;
}
}
ab (alb&1) c=1;
ooo (dd i=0;i<26;i++) {
ans+=b[i]&1;
}
ab (c&&ans==1) printf("yes !\n");
wow ab (c&&ans!=1) printf("no...\n");
wow ab (c==0&&ans!=0) printf("no...\n");
wow printf("yes !\n");
}
}