Codeforces Round #438A

#include "iostream"
#include "iomanip"
#include "string.h"
#include "stack"
#include "queue"
#include "string"
#include "vector"
#include "set"
#include "map"
#include "algorithm"
#include "stdio.h"
#include "math.h"
#pragma comment(linker, "/STACK:102400000,102400000")
#define bug(x) cout<<x<<" "<<"UUUUU"<<endl;
#define mem(a,x) memset(a,x,sizeof(a))
#define step(x) fixed<< setprecision(x)<<
#define mp(x,y) make_pair(x,y)
#define pb(x) push_back(x)
#define ll long long
#define endl ("\n")
#define ft first
#define sd second
#define lrt (rt<<1)
#define rrt (rt<<1|1)
using namespace std;
const ll mod=1e9+7;
const ll INF = 1e18+1LL;
const int inf = 1e9+1e8;
const double PI=acos(-1.0);
const int N=1e5+100;

char a,b,s[105],t[105];
int n;
int main(){
    cin>>a>>b>>n;
    for(int i=1; i<=n; ++i){
        cin>>s[i]>>t[i];
    }
    int f1=0, f2=0;
    for(int i=1; i<=n; ++i){
        if(t[i]==a) f1=1;
        if(s[i]==b) f2=1;
        if(s[i]==a && t[i]==b){
            cout<<"YES\n";
            return 0;
        }
    }
    if(f1==1 && f2==1) cout<<"YES\n";
    else cout<<"NO\n";
    return 0;
}