#include 
      
        #include 
       
         #include 
        
          using namespace std; int map[510][510] = {
    0}; int match[510] = {
    0}; int value[510] = {
    0}; int n = 0; int m = 0; int x = 0; int y = 0; int find(int q) {
    for(int i = 1;i <= n; ++i)     {
    if(value[i] == 0 &&map[q][i])         {
                value[i] = 1; if(match[i] == -1||find(match[i]))             {
                    match[i] = q; return 1;             }         }     } return 0; } int main() {
    while(~scanf("%d%d",&n,&m))     {
            memset(map,0,sizeof(map));         memset(match,-1,sizeof(match)); for(int i = 1;i <= m;++i)         {
                scanf("%d%d",&x,&y);             map[x][y] = 1;         } int ans = 0; for(int i = 1;i <= n;++i)         {
                memset(value,0,sizeof(value)); if(find(i))         ++ans;         }         printf("%d\n",ans);     } return 0; }