#include <stdio.h>
#include <string.h>
#include <string>
#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <algorithm>
#include <stack>
#include <assert.h>
using namespace std;const int N=44;int n;
vector<pair<int,int> > g[N];int a[N],m;
int b[N];
int c[N];int dfs(int t)
{for(int i=0;i<(int)g[t].size();++i){int v=g[t][i].first;int w=g[t][i].second;if(b[v]==-1){b[v]=w^b[t];if(!dfs(v)) return 0;}else if(b[v]!=(w^b[t])) return 0;}return 1;
}int get()
{for(int i=0;i<m;++i) g[i].clear();for(int i=0;i<m;++i) {for(int j=i+1;j<m;++j) {g[i].push_back(make_pair(j,a[i]^a[j]));g[j].push_back(make_pair(i,a[i]^a[j]));}}int ans=m+1;for(int i=0;i<2;++i){memset(b,-1,sizeof(b));b[0]=i;if(!dfs(0)) return -1;int all=0;for(int i=0;i<m;++i) all^=b[i];int ok=1;for(int i=0;i<m&&ok;++i){if(a[i]!=(all^b[i])) ok=0;}if(!ok) continue;int tmp=0;for(int i=0;i<m;++i) tmp+=b[i];if(ans>tmp) ans=tmp;}if(ans==m+1) ans=-1;return ans;
}int cal()
{m=0;int k=0;for(int i=0;i<n;++i){if(c[i]==-1) k=1;else a[m++]=c[i];}if(k){++m;a[m-1]=0;int p0=get();a[m-1]=1;int p1=get();if(p0==-1){if(p1==-1) return -1;return p1;}else{if(p1==-1) return p0;return min(p0,p1);}}else{return get();}
}class OthersXor
{
public:long long minSum(vector<int> x){n=(int)x.size();long long sum=0;for(int i=0;i<30;++i){for(int j=0;j<n;++j){if(x[j]==-1) c[j]=-1;else c[j]=(x[j]>>i)&1;}int p=cal();if(p==-1) return -1;sum+=(1ll<<i)*p;}return sum;}
};

#include <stdio.h>
#include <string.h>
#include <string>
#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <algorithm>
#include <stack>
#include <assert.h>
using namespace std;vector<int> g[1005];
int n;
int s,t;queue<int> Q;
int f[1005];int bfs()
{memset(f,-1,sizeof(f));f[0]=0;Q.push(0);while(!Q.empty()){int u=Q.front(); Q.pop();for(int i=0;i<(int)g[u].size();++i){int v=g[u][i];if(f[v]==-1){f[v]=f[u]+1;Q.push(v);}}}if(f[t]!=-1) return f[t]-1;return f[t];
}int gcd(int a,int b)
{return !b?a:gcd(b,a%b);
}class FromToDivisible
{
public:int shortest(int N,int S,int T,vector<int> a,vector<int> b){n=(int)a.size();s=0;t=n+1;for(int i=0;i<n;++i) for(int j=0;j<n;++j) if(i!=j){long long tmp=1ll*b[i]/gcd(b[i],a[j])*a[j];if(tmp<=N){g[i+1].push_back(j+1);}}for(int i=0;i<n;++i){if(S%a[i]==0) g[0].push_back(i+1);if(T%b[i]==0) g[i+1].push_back(t);}return bfs();}
};