func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, d = 2;   bool P[100100];   int A[100100];   vector<pair<int, int> > R;   void criba() {     for (int i = 0; i < 100100; i++) P[i] = 1;     P[0] = 0;     P[1] = 0;     for (int i = 2; i < 100100; i++) {       if (P[i]) {         for (int j = 2 * i; j < 100100; j += i) P[j] = 0;       }     }   }   void solve(int a, int b) {     if (a == b) return;     if (a > b) swap(a, b);     for (int i = b; i > a; i--)       if (P[i - a + 1]) {         swap(A[a], A[i]);         R.push_back(make_pair(a, i));         solve(i, b);         break;       }   }   int main() {     cin >> n;     for (int i = 1; i <= n; i++) cin >> A[i];     criba();     for (int i = 1; i <= n; i++) {       while (A[i] != i) solve(i, A[i]);     }     cout << R.size() << endl;     for (int i = 0; i < R.size(); i++) {       cout << R[i].first <<     << R[i].second << endl;     }     return 0;   }   