#include <iostream>
#include <cstring>
#include <vector>
#define MAX 205

using namespace std;

void dfs(int p);
vector <int> a[MAX];
int num[MAX];
int dp[MAX][2];
int f[MAX][2];

int main()
{
    string name[MAX];
    string boss;
    char temp1[MAX], temp2[MAX];
    int n;
    int i, j;
    while (scanf("%d", &n) && n)
    {
        memset(dp, 0, sizeof(dp));
        memset(num, 0, sizeof(num));
        memset(temp1, '\0', sizeof(temp1));
        memset(temp2, '\0', sizeof(temp2));
        scanf("%s", temp1);
        name[0] = temp1;
        for (i=1; i<n; i++)
        {
            scanf("%s %s", temp1, temp2);
            name[i]  = temp1;
            boss = temp2;
            num[i] = i;
            for (j=0; j<n; j++)
            {
                if (name[j] == boss)
                {
                    a[j].push_back(num[i]);
                    a[i].push_back(num[j]);
                    break;
                }
            }
        }
        dfs(a[0][0]);
        memset(f, 1, sizeof(f));
        if (dp[0][0] > dp[0][1])
        {
            if (f[0][0] == 0)
            {
                printf("%d No\n", dp[0][0]);
            }

            else printf("%d Yes\n", dp[0][0]);
        }

        else if (dp[0][0] == dp[0][1])
        {
            printf("%d No\n", dp[0][0]);
        }


        else
        {
            if (f[0][1] == 0)
            {
                printf("%d No\n", dp[0][1]);
            }

            else printf("%d Yes\n", dp[0][1]);
        }
        for (i=0; i<MAX; i++)
        {
            a[i].clear();
        }
    }

    return 0;
}

void dfs(int p)
{
    unsigned int i;
    for (i=0; i<a[p].size(); i++)
    {
        if (num[a[p][i]] != -1)
        {
            num[a[p][i]] = -1;
            dfs(a[p][i]);

            dp[p][1] += dp[a[p][i]][0];
            if (f[a[p][i]][0] == 0)
            {
                f[p][1] = 0;
            }

            dp[p][0] += max(dp[a[p][i]][1], dp[a[p][i]][0]);
            if (dp[a[p][i]][1] == dp[a[p][i]][0])
            {
                f[p][0] = 0;
            }
        }
    }
    dp[p][1]++;
    return;
}