#include <iostream>  
#include <stdio.h>  
using namespace std;  
const int MAXN = 30;  
int n, ok, c[MAXN], data[MAXN][MAXN];  
int check(int x){  
    for (int i = 1; i <= n; ++i){  
        if ((data[x][i] && c[i] != c[x]) || (!data[x][i])) continue;  
        return 0;  
    }  
    return 1;  
}  
void search(int id, int color){  
    if (id == n + 1){  
        ok = 1; return;  
    }  
    if (ok) return;  
    for (int i = 1; i != color + 1; ++i){  
        c[id] = i;  
        if (check(id)) search(id + 1, color);  
    }  
    c[id] = 0;  
}  
int main(){  
    char ch, tch;  
    int x, y;  
    while (cin >> n && n != 0){  
        tch = getchar();  
        memset(data, 0, sizeof(data));  
        for (int i = 0; i != n; ++i){  
            ch = getchar();  
            x = ch - 'A' + 1;  
            tch = getchar();  
            while (ch = getchar()){  
                if (ch < 'A') break;  
                y = ch - 'A' + 1;  
                data[x][y] = data[y][x] = 1;  
            }  
        }  
        for (int i = 1; i <= 4; ++i){  
            memset(c, 0, sizeof(c));  
            ok = 0; search(1, i);  
            if (ok){  
                if (i == 1) cout << "1 channel needed." << endl; else cout << i << " channels needed." << endl;  
                break;  
            }  
        }  
    }  
    return 0;  
}