import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner=new Scanner(System.in);
while(scanner.hasNext()){
int n=scanner.nextInt();
int a[]=new int[n];
for (int i = 0; i < n; i++) {
a[i]=scanner.nextInt();
}
int max=0;
int s;
int t=1000000,num;
for (int i = 1; i < n-1; i++) {
s=a[i]-a[i-1];
if (s>max) {
max=s;
}
if(a[i+1]-a[i-1]<t){
t=a[i+1]-a[i-1];
}
}
System.out.println(Math.max(Math.max(max, a[n-1]-a[n-2]),t));
}
}
}