#include<cstdio>

#include<cmath>

#include<vector>

#include<map>

#include<set>

#include<algorithm>

#include<cstring>

using namespace std;

//#define local

typedef long long  ll;

const int maxn = +;

#define lowbit(x) ((x)&-(x))

ll C[maxn];

ll n,a,b;

void add(ll x,ll d)

{

    while(x <= n) {

        C[x]+=d; x+=lowbit(x);

    }

}

ll sum(ll x)

{

    ll ret = ;

    while(x > ){

        ret += C[x]; x-=lowbit(x);

    }

    return ret;

}

ll Count()

{

    ll res = ;

    ll ele = b;

    for(int i = ; i < n; i++){

        ll pre = sum(ele+);

        res += ele - pre;

        add(ele+,);

        ele = (ele+a)%n;

    }

    return res;

}

int main()

{

#ifdef local

    freopen("in.txt","r",stdin);

    //freopen("out.txt","w",stdout);

#endif // local

    int cas = ;

    while(~scanf("%I64d%I64d%I64d",&n,&a,&b)&&n){

        memset(C,,sizeof(C));

        printf("Case %d: %I64d\n",++cas,Count());

    }

    return ;

}