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

int solution(int* nums, int numsSize, int k) {
    int maxSum = INT_MIN;
    
    // Try all possible starting positions
    for (int i = 0; i < numsSize; i++) {
        // Try all possible ending positions
        for (int j = i; j < numsSize; j++) {
            int length = j - i + 1;
            // Check if length is divisible by k
            if (length % k == 0) {
                // Calculate sum of subarray
                int currentSum = 0;
                for (int m = i; m <= j; m++) {
                    currentSum += nums[m];
                }
                if (currentSum > maxSum) {
                    maxSum = currentSum;
                }
            }
        }
    }
    
    return maxSum;
}

void parseArray(const char* str, int* arr, int* size) {
    *size = 0;
    const char* p = str;
    while (*p && *p != '[') p++;
    if (*p == '[') p++;
    while (*p && *p != ']') {
        while (*p == ' ' || *p == ',') p++;
        if (*p == ']' || *p == '\0') break;
        arr[(*size)++] = (int)strtol(p, (char**)&p, 10);
    }
}

int main() {
    char line[10000];
    fgets(line, sizeof(line), stdin);
    
    // Parse array manually
    int nums[1000];
    int numsSize = 0;
    char* token = strtok(line, "[,]");
    while (token != NULL) {
        nums[numsSize++] = atoi(token);
        token = strtok(NULL, "[,]");
    }
    
    int k;
    scanf("%d", &k);
    
    int result = solution(nums, numsSize, k);
    printf("%d\n", result);
    
    return 0;
}