public void solve(int testNumber, InputReader in, OutputWriter out) {
count = in.readInt();
from = new int[count];
to = new int[count];
IOUtils.readIntArrays(in, from, to);
previousSame = new int[count];
for (int i = 0; i < count; i++) {
for (int j = 0; j < i; j++) {
if (from[i] == from[j] && to[i] == to[j] || from[i] == to[j] && to[i] == from[j])
previousSame[i] += 1 << j;
}
}
result = new long[8][8][1 << count];
ArrayUtils.fill(result, -1);
long answer = 0;
for (int i = 0; i < count; i++) {
if (previousSame[i] == 0) {
answer += go(from[i], to[i], (1 << count) - 1 - (1 << i));
if (from[i] != to[i]) answer += go(to[i], from[i], (1 << count) - 1 - (1 << i));
}
}
out.printLine(answer);
}
