#include <iostream>

#include <sstream>

#include <algorithm>

#include <cstdio>

#include <math.h>

#include <set>

#include <map>

#include <queue>

#include <string>

#include <string.h>

#include <bitset>

#define REP(i,a,n) for(int i=a;i<=n;++i)

#define PER(i,a,n) for(int i=n;i>=a;--i)

#define hr putchar(10)

#define pb push_back

#define lc (o<<1)

#define rc (lc|1)

#define mid ((l+r)>>1)

#define ls lc,l,mid

#define rs rc,mid+1,r

#define x first

#define y second

#define io std::ios::sync_with_stdio(false)

#define endl '\n'

#define DB(a) ({REP(__i,1,n) cout<<a[__i]<<' ';hr;})

using namespace std;

typedef long long ll;

typedef pair<int,int> pii;

const int P = 1e9+7, P2 = 998244353, INF = 0x3f3f3f3f;

ll gcd(ll a,ll b) {return b?gcd(b,a%b):a;}

ll qpow(ll a,ll n) {ll r=1%P;for (a%=P;n;a=a*a%P,n>>=1)if(n&1)r=r*a%P;return r;}

ll inv(ll x){return x<=1?1:inv(P%x)*(P-P/x)%P;}

inline int rd() {int x=0;char p=getchar();while(p<'0'||p>'9')p=getchar();while(p>='0'&&p<='9')x=x*10+p-'0',p=getchar();return x;}

//head

const int N = 1e6+10;

int n, m, nxt[N][26], f[26];

char s1[N], s2[N];

int main() {

	scanf("%s%s", s1+1, s2+1);

	n = strlen(s1+1), m = strlen(s2+1);

	REP(i,1,m) if (s1[i]!=s2[i]) return puts("No"),0;

	for (int i=n,now=m; s2[now]==s2[m]; --now,--i) {

		if (s1[i]!=s2[m]) return puts("No"),0;

	}

	int x = s2[m];

	PER(i,1,m) {

		if (!f[s2[i]-'a']) f[s2[i]-'a'] = x;

		x = s2[i];

	}

	REP(i,0,25) nxt[n+1][i]=nxt[n+2][i]=n+1;

	PER(i,1,n) {

		memcpy(nxt[i],nxt[i+1],sizeof nxt[0]);

		nxt[i][s1[i]-'a']=i;

	}

	REP(i,m+1,n) if (s1[i]!=s2[m]) {

		if (!f[s1[i]-'a']) return puts("No"),0;

		if (nxt[i][f[s1[i]-'a']-'a']>n) return puts("No"),0;

	}

	puts("Yes");

}