#include<stdio.h> int suShu(int x){ if(x>1){ int i,c=0; for(i=2;i<=x/2;i++){ if(x%i==0){ c++; break; } } if(c==0) return 1; else return 0; }else{ return 0; } } int main(){ int n,i; scanf("%d",&n); for(i=2;i<=n;i++){ if(suShu(i)==1&&suShu(i+2)==1&&(i+2)<=n){ printf("%d %d\n",i,i+2); } } return 0; } /************************************************************** Problem: 1139 User: admin Language: C Result: Accepted Time:16 ms Memory:1144 kb ****************************************************************/