#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cstdio>
using namespace std;
typedef long long ll;
int mod = 1e9 + 7;

int main(void)
{
    string n, m;
    cin >> n >> m;
    string a = m.substr(0, m.size() - 1);
    if(n==a&&m[m.size()-1]=='0')
        cout << "Yes" << endl;
        else
            cout << "No" << endl;
        return 0;
}