#include<bits/stdc++.h>
using namespace std;
struct{
int x;
}tr[114];
long long n,s;
long long a1,a2,q1,q2,t1,t2;
vector<long long> v[514];
inline void qs(int i){
s++;
if(tr[i].x!=0) qs(tr[i].x);
}
inline int sq(int i){
if(t2==t1) return i;
t2--;
return sq(tr[i].x);
}
inline int fa(int i,int j){
if(tr[i].x==tr[j].x) return tr[i].x;
if(tr[i].x!=0&&tr[j].x!=0) return fa(tr[i].x,tr[j].x);
}
int main(){
cin>>a1>>a2>>n;
for(int i=1;i<=n;i++){
cin>>q1>>q2;
tr[q1].x=q2;
}
qs(a1);
t1=s;
s=0;
qs(a2);
t2=s;
if(t1>t2) swap(t1,t2),swap(a1,a2);
a2=sq(a2);
if(a1==a2) cout<<a1;
else cout<<fa(a1,a2);
}