func_code_string: #include <bits/stdc++.h>   using namespace std;   long long int is_prime[1000500];   int main() {     for (long long int i = 0; i < ((long long int)(1000500)); ++i)       if (2 <= i) is_prime[i] = true;     for (long long int i = 2; i * i < 1000500; i++) {       if (!is_prime[i]) continue;       for (long long int j = i * i; j < 1000500; j += i) is_prime[j] = false;     }     long long int a, b, k;     cin >> a >> b >> k;     queue<long long int> q;     long long int res = -1;     q.push(a - 1);     for (long long int pos = a; pos <= b; pos++) {       if (is_prime[pos]) q.push(pos);       while (k < ((long long int)(q).size())) q.pop();       if (((long long int)(q).size()) == k) res = max(res, pos - q.front() + 1);     }     if (q.front() == a - 1)       cout << -1 << endl;     else       cout << res << endl;   }   