#include <bits/stdc++.h>
using namespace std;
#define F(X, Y) for(int X = 0; X < Y; X++)
array<int, 2> g[1<<20];
int N, p, j;
struct Solver {
int e[1<<20], d[1<<20] = {};
int maxDeg = 0, cycle = -1, rem = N;
void add(int u, int v) {
if(u == rem || v == rem || maxDeg > 2) return;
maxDeg = max({maxDeg, ++d[u], ++d[v]});
while(e[u] >= 0) u = e[u];
while(e[v] >= 0) v = e[v];
if(u == v)
cycle = cycle < 0 ? u : N;
else {
if(e[u] > e[v]) swap(u, v);
e[u] += e[v], e[v] = u;
}
}
int get() {
if(maxDeg > 2) return 0;
return cycle < 0 ? N : e[cycle];
}
} s[5];
void Init(int n) {
F(i, 5) fill(s[i].e, s[i].e+(N=n), -1);
}
void Link(int A, int B) {
if(!p) {
s[0].add(A, B);
g[j++] = {A, B};
if(s[0].maxDeg > 2) {
F(i, N)
if(s[0].d[i] > 2) s[p=1].rem = i;
F(k, j) F(i, 2)
if(g[k][i] == s[1].rem) s[++p].rem = g[k][!i];
F(i, 4) F(k, j)
s[i+1].add(g[k][0], g[k][1]);
}
} else
F(i, 4) s[i+1].add(A, B);
}
int CountCritical() {
int res = 0;
if(p) F(i, 4)
res += s[i+1].get() > 0;
else res = abs(s[0].get());
return res;
}
