/*
TASK:store
LANG:C++
*/
#include<stdio.h>
int i,j,k,f,s,n,z,m,br;
int main()
{
scanf("%d%d",&n,&m);
 for (i=0;i<n;i++)
  {scanf("%d%d",&f,&s);
  br+=f;
    if (s!=0) for (j=0;j<s;j++)
			  scanf("%d",&z);
  }
   




printf("%d\n",br/2);
return 0;                 
}

                 
