#include<stdio.h>

int main()
{
	int n,i,j,diff,c=0;
	scanf("%d",&n);
	int a[n];
	for(i=0;i<n;i++)
		scanf("%d",&a[n]);
		for(i=0;i<n;i++)
		{
			for(j=i+1;j<=n;j++)
			{
				if(a[i]>a[j])
				diff=a[i]-a[j];
				if(a[i]<=a[j])
					diff=a[j]-a[i];
				if(diff<=1)
					c++;
			}
		}
	         printf("%d",c);
	         return 0;

}