# include <cstdio># include <cstring>const int maxn = 505;int n, k;int c[maxn];bool g[maxn][maxn];bool vis[maxn];int mark[maxn];bool find(int u) {    for (int v = 1; v <= n; ++v) if(g[u][v]){        if (vis[v]) continue;        vis[v] = true;        if (mark[v]==-1 || find(mark[v])) {            mark[v] = u;            return true;        }    }    return false;}int main(){    while (scanf("%d%d", &n, &k) != EOF) {        memset(c, 0, sizeof(c[0])*(n+1));        for (int i = 1; i <= n; ++i) memset(g[i], false, sizeof(g[i][0])*(n+1));        for (int i = 0, x, y; i < k; ++i) {            scanf("%d%d", &x, &y);            g[x][y] = true;        }        int ans = 0;        memset(mark, -1, sizeof(mark[0])*(n+1));        for (int i = 1; i <= n; ++i) {            memset(vis, false, sizeof(vis[0])*(n+1));            if (find(i)) ++ans;        }        printf("%d\n", ans);    }    return 0;}