uva12545

#include<iostream>  

using namespace std; 
 
const int maxn =100+10;  

char s[maxn],t[maxn];  

int  main(){  
    //freopen("10.in", "r", stdin);
    //freopen("10.out", "w", stdout);
    int n;  
    cin >> n;   
    for(int i = 1; i <= n; i ++){  
        cin >> s >> t;  
        cout << "Case " << i << ": ";  
        int s1 = 0, t1 = 0, q1 = 0, num = 0;  
        int len = strlen(s);  
        for(int j = 0; j < len; j ++){
            if(t[j] == '0') t1 ++;  
            if(s[j] == '0') s1 ++;  
            if(s[j] == '?'){  
                q1 ++;  
                num ++;  
            }  
            if(s[j] == '?' && t[j] == '0'){  
                s[j] = '0';  
                s1 ++;  
                q1 --;  
            }  
        }  
        if(s1 + q1 < t1){  
            cout << "-1" << endl;  
            continue;  
        }  
        int sum = t1 - s1;  
        int s0 = 0, s2 = 0;  
        for(int k = 0; k < len; k ++){  
            if(s[k] == '0' && t[k] == '1') s0++;  
        }  
        if(sum > 0){  
            s0 += sum;  
        }  
        num += s0;  
        cout << num << endl;  
    }  
    return 0;  
}