int findd(int data){
    int l = 1, r = n;
    while (r - l > 1){
        int mid = (l + r) >> 1;
        if (q[mid] > data)
            r = mid;
        else l = mid;
    }
    if (q[l] == data) return l;
    if (q[r] == data) return r;
    return 0;
}

 ++n;
        x[1] = a+b; q[1] = a+b;
        x[2] = a-b; q[2] = a-b;
        for (int i = 3; i <= n; ++i){
            x[i] = (a*x[i-2] + b*x[i-1])%m;
            q[i] = x[i];
        }
        for (int i = 1; i <= n; ++i)
            x[i] = findd(x[i]);