#include<stdio.h>
int a[1000000],n,m,i,k,x,i1,i2,este,min,o,p,nr,zr;
int read()
{
    for(i=1;i<=n;i++)
   { if(scanf("%d",&x),x!=a[m])
    a[++m]=x;
    if(x==0)
    zr=1;
}
}
int main ()
{
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
    scanf("%d",&n);
    m=0;
    a[0]=-1;
    read();

    for(i=2;i<=m;i++)
 {  if(a[i]!=a[i-1] && a[i]!=0 && a[i-1] !=0)
    nr++;
    else
    if(a[i-1]==0 && a[i]!=0)
    nr++;
}
  // for(i=1;i<=m;i++)
  //  printf("%d ",a[i]);
    printf("%d\n",nr-1);

    return 0;
}