#include<stdio.h>

main()
{

    int n,k,d;

     scanf("%d %d",&n,&k);
     scanf("%d",&d);
     int a[d];

     for(int i=0;i<d;i++)
        scanf("%d",&a[i]);

     int length = sizeof(a)/sizeof(a[0]);

     printf("%d\n",n-length);

}
