#include <bits/stdc++.h>
char s[105];
int main() {
  scanf("%s", s);
  int len = strlen(s), n1 = 0, n2 = 0;
  for (int i = 0; i < len; i++)
    if (s[i] == 'o')
      n1++;
    else if (s[i] == '-')
      n2++;
  if (n1 == 0)
    printf("YES");
  else if (n2 % n1 == 0)
    printf("YES");
  else
    printf("NO");
  return 0;
}
