Link to this code:
https://cses.fi/paste/2e4f33786d1cfccac4a966/
//Слава Україні, Героям слава
#include <bits/stdc++.h>
using namespace std;
int v[32];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n, k;
cin >> n >> k;
int x, a, b, c;
cin >> x >> a >> b >> c;
int l = x, r = x, res = 0, ans = 0;
for(int i = 0; i < k; i++) {
int rr = r;
for(int j = 0; j < 31; j++) {
v[j] += (rr & 1);
rr >>= 1;
}
res |= r;
r = (1ll * r * a + b) % c;
}
ans = res;
for(int i = 0; i < n - k; i++) {
int ll = l, rr = r;
for(int j = 0; j < 31; j++) {
v[j] += (rr & 1) - (ll & 1);
res ^= (1 << j) * (v[j] == 0) * (ll & 1);
rr >>= 1;
ll >>= 1;
}
res |= r;
ans ^= res;
l = (1ll * l * a + b) % c;
r = (1ll * r * a + b) % c;
}
cout << ans << "\n";
return 0;
}