#include<bits/stdc++.h>
using namespace std;
const long long mod=1e9+7;
long long fastpower(long long a,long long b){
	long long ans=1;
	while(b){
		if(b&1) ans=ans*a%mod;
		a=a*a%mod;
		b/=2;
	}
	return ans;
}
long long f[1000010];
long long inv3;
void solve(){
	string s,t;
	int k;
	cin>>s>>t>>k;
	int n=max(t.size(),s.size());
	vector<int> a,b,c;
	int d[n+10];
	for(int i=s.size()-1;i>=0;i--) a.push_back(s[i]-'0');
	for(int i=t.size()-1;i>=0;i--) b.push_back(t[i]-'0');
	for(int i=0;i<n;i++){
		if(i>=a.size()) a.push_back(0);
		if(i>=b.size()) b.push_back(0);
		c.push_back(a[i]^b[i]);
	}
	int cnt=0,j=0;
	for(int i=0;i<c.size();i+=2){
		if(i+1==c.size()) c.push_back(0);
		if(c[i]==1&&c[i+1]==0) d[j]=1;
		if(c[i]==1&&c[i+1]==1) d[j]=2;
		if(c[i]==0&&c[i+1]==1) d[j]=3;
		if(c[i]==0&&c[i+1]==0) d[j]=4;
		if(d[j]&&!cnt) cnt=i/2+1;
		j++;
	}
	if(cnt==0){
		if(k-1>=1000000) cout<<(fastpower(4,k)-4)*inv3%mod<<endl;
		else cout<<(f[k-1]-1+mod)%mod<<endl;
		return ;
	}
	if(k>cnt) {
		cout<<-1<<endl;
		return ;
	}
	long long ans=0;
	ans=(fastpower(4,k)-4)*inv3%mod;
	for(int i=0;i<d.size();i++){
		ans=(ans+d[i]*f[i]%mod)%mod;
	}
	cout<<ans<<endl;
}
int main(){
	inv3=fastpower(3,mod-2);
	f[0]=1;
	for(int i=1;i<=1000000;i++){
		f[i]=(f[i-1]*4%mod+1)%mod;
	}
	int t;
	cin>>t;
	while(t--){
		solve();
	}
	return 0;
}

answer.code: In function ‘void solve()’:
answer.code:50:25: error: request for member ‘size’ in ‘d’, which is of non-class type ‘int [(n + 10)]’
   50 |         for(int i=0;i<d.size();i++){
      |                         ^~~~