#include <bits/stdc++.h>
using namespace std;
int SNT(int n)
{
if(n < 2) return 0;
int dem = 0;
for(int i = 2; i <= sqrt(n); i++)
{
if(n % i == 0)
return 0;
}
return 1;
}
int main()
{
int n, a, b;
while(cin >> n)
{
a = -1000000000;
for(int i = n; i >= 1; i--)
{
if(SNT(i) == 1)
{
a = i;
break;
}
}
for(int i = n; i<= n + 10000000; i++)
{
if(SNT(i) == 1)
{
b = i;
break;
}
}
if(n - a <= b - n)
cout << a << endl;
else cout << b << endl;
}
}
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