tioj 1253

#pragma GCC optimzize("Ofast,no-stack-protector")
#include<bits/stdc++.h>
#define int long long
#define quick ios::sync_with_stdio(0);cin.tie(0);
#define rep(x,a,b) for(int x=a;x<=b;x++)
#define repd(x,a,b) for(int x=a;x>=b;x--)
#define lowbit(x) (x&-x)
#define sz(x) (int)(x.size())
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define mp make_pair
#define eb emplace_back
using namespace std;
typedef pair<int,int> pii;
void debug(){
    cout<<"\n";
}
template <class T,class ... U >
void debug(T a, U ... b){
    cout<<a<<" ",debug(b...);
}
const int N=1e3+7;
const int INF=1e18;
vector<int> v[N];//X的鄰點
int match[N]; // Y所匹配的節點
bool vis[N]; //在這次尋找中是否被走過
int dfs(int x){
    for(int y:v[x]){
        if(vis[y]) continue;
        vis[y]=true;
        if(match[y]==-1||dfs(match[y])){
            match[y]=x;
            return true;
        }
    }
    return false;
}
int bipartiteMatching(int n){
    fill(match,match+n+1,-1);
    int ans=0;
    rep(i,1,n){
        fill(vis,vis+n+1,0);
        if(dfs(i)) ans++;
    }
    return ans;
}
signed main(){
    quick
    int n,k;
    int Case=1;
    while(cin>>n>>k&&n&&k){
        fill(v,v+n+1,vector<int>());
        while(k--){
            int a,b;
            cin>>a>>b;
            v[a].eb(b);
        }
        cout<<"Case #"<<Case++<<":"<<bipartiteMatching(n)<<"\n";
    }
    return 0;
}