#include<bits/stdc++.h>
using namespace std;
int main() {
string S;
cin >> S;
int count[26][101] = {0};
// 更新count数组
for (int i = 0; i < S.size(); i++) {
char c = S[i];
count[c - 'a'][++count[c - 'a'][0]]++;
}
int flag = 0;
for (int i = 1; i <= S.size(); i++) {
int unique_chars = 0;
for (int j = 0; j < 26; j++) {
if (count[j][i] > 0) {
unique_chars++;
}
}
if (unique_chars == 1) {
flag = 1;
break;
}
}
if (flag == 0) {
cout << "Yes" << endl;
} else {
cout << "No" << endl;
}
return 0;
}
/**
* _ooOoo_
* o8888888o
* 88" . "88
* (| -_- |)
* O\ = /O
* ____/`---'\____
* .' \\| |// `.
* / \\||| : |||// \
* / _||||| -:- |||||- \
* | | \\\ - /// | |
* | \_| ''\---/'' | |
* \ .-\__ `-` ___/-. /
* ___`. .' /--.--\ `. . __
* ."" '< `.___\_<|>_/___.' >'"".
* | | : `- \`.;`\ _ /`;.`/ - ` : | |
* \ \ `-. \_ __\ /__ _/ .-` / /
* ======`-.____`-.___\_____/___.-`____.-'======
* `=---='
* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
帮个忙吧 QaQ
* | | |
* | | |
* | | |
* ===========
* / \
* | \
* \_____________/
**/