'''
Don't Copy This Code, Try To Solve It By Yourself
'''
def Solve():
ss, rs = [], []
for t in range(int(input())):
ss.append(input())
rs.append(input())
for s, r in zip(ss, rs):
if "a" in s:
if r=="a":
print(1)
elif "a" in r:
print(-1)
else:
print(2**len(s))
else:
print(0)
if __name__ == "__main__":
Solve()#include<bits/stdc++.h>
#define T int t; cin>>t; while(t--)
#define ll long long int
#define endl "\n"
#define eb emplace_back
#define ff first
#define ss second
#define M 1000000007
#define yess {cout<<"YES"<<endl;return;}
#define nos {cout<<"NO"<<endl;return;}
#define print(n) {cout<<n<<endl;return;}
#define input ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(0);
using namespace std;
void sol(){
cout<<fixed<<setprecision(25);
string s,t;cin>>s>>t;
if(t=="a")print(1)
for(int i=0;i<t.size();i++){
if(t[i]=='a')print(-1)
}
ll ans=(pow(2,s.size()));
print(ans)
/////////////////
}
int main(){
input
T sol();
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