#include <iostream>
using namespace std;

int main() {
	int arr[]= {1, 5, 3, 4, 2};
	int n=sizeof(arr)/sizeof(arr[0]);
	int diff=2;
	int count=0;
	for(int i=0;i<n-1;i++){
		for(int j=i+1;j<n;j++){
			if(abs(arr[i]-arr[j])==diff)
				count++;
		}
	}
	cout<<count;
}