#include <iostream>
#include <vector>
#include <queue>

int r = 0;
vector<int> mat[100001];
bool p[100001];

queue<nod> q;

void bfs()
{
    viz[q.front()] = 1;

    while(!q.empty())
    {
        nod c = q.front();
        q.pop();

        for(int it : mat[c])
        {
            if(viz[it] == 0)
            {
                viz[it] = 1;
                q.push(it);
            }
        }
    }
}

int main()
{
    cin >> N;
    for(int i = 1; i<=N; i++)
        cin << mat[i].val;

    int a, b;
    while(cin >> a >> b)
    {
        mat[a].push_back(b);
        p[b] = 1;
    }



    for(int i = 1; i<=N; i++)
        if(p[b] == 0)
        {
            r = i;
            break;
        }

    q.push(r);
    bfs();







}