#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int solution(int* nums, int numsSize, int k) {
    if (numsSize == 0) return 0;
    
    int minVal = nums[0], maxVal = nums[0];
    for (int i = 1; i < numsSize; i++) {
        if (nums[i] < minVal) minVal = nums[i];
        if (nums[i] > maxVal) maxVal = nums[i];
    }
    
    // The optimal strategy is to:
    // - Increase minVal by k to make it minVal + k
    // - Decrease maxVal by k to make it maxVal - k
    // New range would be (maxVal - k) - (minVal + k) = maxVal - minVal - 2k
    
    int newRange = maxVal - minVal - 2 * k;
    
    // If the new range is negative or zero, we can make all elements equal
    return newRange > 0 ? newRange : 0;
}

int main() {
    char line[1000];
    fgets(line, sizeof(line), stdin);
    
    int nums[100];
    int numsSize = 0;
    
    // Parse JSON array [num1,num2,...]
    char* p = line;
    // Skip to '['
    while (*p && *p != '[') p++;
    if (*p == '[') p++;
    
    // Parse numbers until ']'
    while (*p && *p != ']') {
        // Skip whitespace and commas
        while (*p == ' ' || *p == ',' || *p == '\n' || *p == '\r') p++;
        if (*p == ']' || *p == '\0') break;
        
        // Parse number
        char* endptr;
        nums[numsSize] = (int)strtol(p, &endptr, 10);
        if (p != endptr) {
            numsSize++;
            p = endptr;
        } else {
            break;
        }
    }
    
    int k;
    scanf("%d", &k);
    
    int result = solution(nums, numsSize, k);
    printf("%d\n", result);
    return 0;
}