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    |  | 讨论 Discussion |  |  
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        |  666 |  
        | #include<cmath> #include<iostream>
 int sushu(int x){
 int i,j,f=1;
 for(i=2;i<=int(sqrt(x));i++){
 if(x%i==0){f=0;break;}
 }
 return f;
 }
 int huiwen(int x){
 int i=0,j,f=1,s,t,c[20]={0};
 s=x;
 while(s>0){i++;c[i]=s%10;s=s/10;}
 for(j=1;j<=i/2;j++)if(c[j]!=c[1+i-j]){f=0;break;}
 return f;
 }
 using namespace std;
 int main(){
 //freopen("p1642.in","r",stdin);
 //freopen("p1642.out","w",stdout);
 int  i,j,k,n,s,x=0,y=0,p,t,f=0,d=0;
 cin>>s; n=s;
 y=n;
 if (y%2==0)y++;
 do{
 y+=2;
 if(sushu(y)&&huiwen(y)){cout<<y;break;}
 }while(1==1);
 //fclose(stdin);
 //fclose(stdout);
 return 0;
 }
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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    |  zzz |  
    | 
	  
		
#include<cmath> 
#include<iostream> 
int sushu(int x){ 
int i,j,f=1; 
for(i=2;i<=int(sqrt(x));i++){ 
if(x%i==0){f=0;break;} 
} 
return f; 
} 
int huiwen(int x){ 
int i=0,j,f=1,s,t,c[20]={0}; 
s=x; 
while(s>0){i++;c[i]=s%10;s=s/10;} 
for(j=1;j<=i/2;j++)if(c[j]!=c[1+i-j]){f=0;break;}  
return f; 
} 
using namespace std; 
int main(){ 
freopen("p1642.in","r",stdin); 
freopen("p1642.out","w",stdout); 
int  i,j,k,n,s,x=0,y=0,p,t,f=0,d=0;  
cin>>s; n=s; 
y=n; 
if (y%2==0)y++;  
do{ 
y+=2; 
if(sushu(y)&&huiwen(y)){cout<<y;break;} 
}while(1==1); 
fclose(stdin); 
fclose(stdout); 
return 0; 
}
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              | Flag |  |  
              | 题号 | P1642 |  
            |  | 模拟 |  
              | 通过 | 59人 |  
              | 提交 | 288次 |  
              | 通过率 | 20% |  
              | 难度 | 1 |  |  |  
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