double WiFi(std::string s1, std::string s2) {
    int n,m,i,j,k,l,r,res,a[2000001],b[201];
    double ans = 0;
    k = 0;
    for (i = 0; i < s1.length(); i++)
    {
        if (s1[i] == '+') k++; else k--;
    }
    j = 0;
    l = 1;
    r = 2;
    for (i = 1; i <= 1000000; i++) a[i] = 0;
    for (i = 0; i < s2.length(); i++)
    {
        if (s2[i] == '+')
        {
            for (j = l; j < r; j++) a[j]++;
        }
        if (s2[i] == '-')
        {
            for (j = l; j < r; j++) a[j]--;
        }
        if (s2[i] == '?')
        {
            for (j = l; j < r; j++)
            {
                a[j*2] = a[j]+1;
                a[j*2+1] = a[j]-1;
            }
            l = r;
            r = r*2;
        }
    }
    j = -1;
    for (i = l; i < r; i++)
    {
        j++;
        a[j] = a[i];
        if (a[i] == k) ans++;
    }
    return ans/(r-l);
}