### Brief description:

nimendongde ..

### Analysis:

…

/* This Code is Submitted by xiaodao for Problem 1004 at 2010-10-24 14:13:43 */ #include <iostream> #include <cmath> using namespace std; const int N = 9999; string s; int x; int l, r; string L(int x){ string res; while (x!=0){ res = char(x%10 + 48) + res; x /= 10; } return res; } string R(int x){ string res; while (x!=0){ res = res + char(x%10 + 48); x /= 10; } return res; } string M(int x){ string res; res = x + 48; return res; } int g(string x){ int res = 0; for (int i=x.size()-1;i>=0;i--) res = res * 10 + (x[i]-48); return res; } bool isPrime(int x){ int t = sqrt(x); for (int i=2;i<=t;i++) if (x%i==0) return false; return true; } void Letsgo(){ for (int i=1;i<=N;i++){ for (int j=0;j<=9;j++){ x = g(L(i) + M(j) + R(i)); if (x > r) return; if (l<=x && x<=r && isPrime(x)) cout << x << endl; } } } int main(){ while (cin >> l >> r){ if (l<=5 && 5<=r) cout << 5 << endl; if (l<=7 && 7<=r) cout << 7 << endl; if (l<=11 && 11<=r) cout << 11 << endl; Letsgo(); } }