func_code_string: #include <bits/stdc++.h>   using namespace std;   long long ab(long long x) { return x > 0LL ? x : -x; }   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     long long n, k, sum = 0, x;     cin >> n >> k;     vector<long long> v;     for (long long i = 0; i < n; i++) {       cin >> x;       sum += x;       v.push_back(x);     }     long long ans = -1;     for (long long i = 0; i < k; i++) {       long long sum2 = 0;       for (long long j = i; j < n; j += k) sum2 += v[j];       ans = max(ans, ab(sum - sum2));     }     cout << ans;     return 0;   }   