B_-_Prefix.cpp

#include<bits/stdc++.h>
using namespace std;

#define endl            "\n"
#define Code            ios_base::sync_with_stdio(false);
#define By              cin.tie(NULL);
#define Nasif           cout.tie(NULL)
#define ll              long long int
#define pb              push_back
#define mp              make_pair
#define Gcd(a,b)        __gcd(a, b)
#define Lcm(a,b)        (a*b) / Gcd(a,b)
#define mem(a,b)        memset(a, b, sizeof(a))//a is array or vector;b is the value that wants to set
#define show(...)       __f (#__VA_ARGS__, __VA_ARGS__)

template <typename Arg1>//show(parameters)
void __f (const char* name, Arg1&& arg1) { cout << name << ": " << arg1 << endl; }
template <typename Arg1, typename... Args>
void __f (const char* names, Arg1&& arg1, Args&&... args){ const char* comma = strchr (names + 1, ',');cout.write (names, comma - names) << ": " << arg1 << " | "; __f (comma + 1, args...);}


int main()
{
    Code By Nasif;
    string s1,s2;
    bool count = false;
    cin>>s1>>s2;
        for(int i=0;i<s1.length();i++ )
    {
        if(s1[i]==s2[i])
        {
            count = true;
        }else 
        {
        count = false;
        break;
        }  
    }    
    if(count)
    {cout<<"Yes";}
    else
    cout<<"No"; 
}