/* */

 # include <iostream>

 # include <cstdio>

 # include <cstring>

 # include <string>

 # include <memory>

 # include <cstdlib>

 # include <cmath>

 # include <climits>

 # include <cctype>

 # include <cassert>

 # include <utility>

 # include <deque>

 # include <queue>

 # include <stack>

 # include <vector>

 # include <bitset>

 # include <set>

 # include <map>

 # include <functional>

 # include <algorithm>

 using namespace std;

  

 # define lson l,m,rt<<

 # define rson m+,r,rt<<|

 # define lowbit(x)(x&(-x))

 # define lcm(a,b)(a*b/__gcd(a,b))

 typedef long long ll;

 const ll mod=1e9+;

 const int maxn=2e5+;

 const double eps=1e-;

 const double pi=acos(-1.0);

 int n, m, c, l;

 int de[maxn];

 vector<int>nex[maxn];

 queue<int>qu;

 int flag[maxn];

  

 int main()

 {

     int t;

     while( ~ scanf("%d%d%d%d", &n, &m, &c, &l) )

     {

         for(int i=; i<=n; i++ )

         {

             nex[i].clear();

             de[i]=;

             flag[i]=;

         }

  

         while( !qu.empty() )

             qu.pop();

         for(int i=; i<=m; i++ )

         {

             int u, v;

             scanf("%d%d", &u, &v);

             nex[u].push_back(v);

             nex[v].push_back(u);

             de[u]++;

             de[v]++;

         }

  

         flag[l]=;

         qu.push(l);

         while( !qu.empty() )

         {

             int cur=qu.front();

             qu.pop();

             for(int i=; i<nex[cur].size(); i++ )

             {

                 de[nex[cur][i]]--;

                 if(  de[nex[cur][i]]<=nex[nex[cur][i]].size()/ && flag[nex[cur][i]]== )

                 {

                     flag[nex[cur][i]] = ;//避免重复入栈

                     qu.push(nex[cur][i]);

                 }

             }

         }

         if( flag[c]== )

             cout<<"leave"<<endl;

         else

             cout<<"stay"<<endl;

     }

     return ;

 }