#include 
#include 
#include 
#include 
using namespace std;
const int maxn = 50005;
int color[maxn];
int invitation[maxn];
vector graph[maxn];
int main(int argc, const char * argv[]) {
    int n;
    cin >> n;
    for(int i = 0; i < n; i++) {
        cin >> invitation[i];
    }
    int m;
    cin >> m;
    for(int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        a--; b--;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    queue q;
    int initial_accepts = 0;
    memset(color, 0, sizeof color);
    for(int i = 0; i < n; i++) {
        if(invitation[i] == 1) {
            color[i] = 1;
            q.push(i);
            initial_accepts++;
        }
        if((int) graph[i].size() == 0) {
            color[i] = 0;
        }
    }
    while(!q.empty()) {
        int node = q.front();
        q.pop();
        if(color[node] == 1) {
            for(int neighbour : graph[node]) {
                if(color[neighbour] == 0) {
                    color[neighbour] = 2;
                    q.push(neighbour);
                }
                else if(color[neighbour] == 1) {
                    color[neighbour] = 3;
                    q.push(neighbour);
                }
            }
        }
        else if(color[node] == 2) {
            for(int neighbour : graph[node]) {
                if(color[neighbour] == 0) {
                    color[neighbour] = 1;
                    q.push(neighbour);
                }
                else if(color[neighbour] == 2) {
                    color[neighbour] = 3;
                    q.push(neighbour);
                }
            }
        }
        else if(color[node] == 3) {
            for(int neighbour : graph[node]) {
                if(color[neighbour] != 3) {
                    color[neighbour] = 3;
                    q.push(neighbour);
                }
            }
        }
    }
    for(int i = 0; i < n; i++) {
        if(color[i] == 3) {
            q.push(i);
        }
    }
    vector visited(n, false);
    while(!q.empty()) {
        int node = q.front();
        q.pop();
        for(int neighbour : graph[node]) {
            if(!visited[neighbour]) {
                visited[neighbour] = true;
                color[neighbour] = 3;
                q.push(neighbour);
            }
        }
    }
    int ones = 0, twos = 0, threes = 0;
    for(int i = 0; i < n; i++) {
        if(color[i] == 1) {
            ones++;
        }
        else if(color[i] == 2) {
            twos++;
        }
        else if(color[i] == 3) {
            threes++;
        }
    }
    int res1 = threes + max(ones, twos);
    cout << max(res1, initial_accepts) << endl;
    return 0;
}