#include<iostream>
#include<cstdio>
#include<bits/stdc++.h>
using namespace std;
string a,b;
int i,len,ans,k,j;
char s[5001];
int main(){
    cin>>a>>b;
    len=a.length();
    for(i=0;i<len;i++){
    	if(b[i]==a[i]){
		   ans++;
		}
		s[i]=a[i];
	}
	if(ans!=len){
		cout<<"No";
		return 0;
	}else if(ans==len){
		for(i=len+1;i<=b.length();i++){
			k=0;
			for(j=0;j<len;j++){
				if(b[i]==s[j]){
					k++;
					break;
				}
			}
			if(k==1){
				cout<<"No";
				return 0;
			}
		}
		cout<<"Yes";
	}
    return 0;
}

样例都过了