1 #include <bits/stdc++.h>
 2 
 3 using namespace std;
 4 const int maxn = 100+10;
 5 int main()
 6 {
 7     char s[maxn],t[maxn];
 8     int x,i,j,kase = 0;
 9     cin >> x;
10     while(x--)
11     {
12         int sum = 0,p = 0,cnt1 = 0,cnt2 = 0;
13         scanf("%s%s",s,t);
14         int len = strlen(s);
15         for(i=0; i<len; i++)
16         {
17             if(s[i]==‘?‘)
18                 p++;
19             if(s[i] == ‘1‘&&t[i]==‘0‘)
20                 cnt1++;
21             else if(t[i]==‘1‘&&s[i]!=‘1‘)
22                 cnt2++;
23         }
24         if(cnt1>cnt2)
25         {
26             printf("Case %d: -1\n",++kase);
27             continue;
28         }
29         sum+=p;
30         int exchange = 0,other = 0;
31         for(i=0; i<len; i++)
32         {
33             if(s[i] == ‘1‘&&t[i]==‘0‘)
34                 exchange++;
35             else if(s[i]==‘0‘&&t[i]==‘1‘)
36                 other++;
37         }
38         sum += max(exchange,other);
39         printf("Case %d: %d\n",++kase,sum);
40     }
41     return 0;
42 }