A

#include<iostream>
#include<map>
#include<vector>
using namespace std;

int c, r;
string s1, s2;
map<string, int> ans;
map<string, vector<string> > graph;
map<string, bool> viz;
vector<string> animals;


int solve(string node){
    viz[node] = true;
    if(graph[node].size() == 0) return ans[node] = 1;

    for(int i=0; i < graph[node].size(); i++){
        string aux = graph[node][i];
        if(viz[aux]) ans[node] = max(ans[node], 1 + ans[aux]);
        else ans[node] = max(ans[node], 1+solve(aux));
    }

    return ans[node];
}

void build(){
    for(int i=0; i < c; i++){
        string aux = animals[i];
        if(!viz[aux]) solve(aux);
    }
}

int search(){
    int tmp = ans[animals[0]];
    for(int i=0; i < c; i++){
        tmp = max(tmp, ans[animals[i]]);
    }
    return tmp;
}

int main(){
    ans.clear(), viz.clear(), animals.clear(), graph.clear();
    cin >> c >> r;
    if(c == 0 and r == 0) return 0;
    for(int i=0; i < c; i++){
        cin >> s1;
        animals.push_back(s1);
    }

    for(int i=0; i < r; i++){
        cin >> s1 >> s2;
        graph[s2].push_back(s1);
    }
    build();
    cout << search() << endl;
    main();
}