#include <stdio.h>

int ss(int num) {
    for (int i = 2; i < num; ++i) {
        if (num%i == 0)
            return 0;
    }
    return num;
}

int main() {
    int num, flag;
    scanf("%d", &num);
    if (num < 2)  // 0和1都不是素数
        num = 2;
    while (1) {
        flag = ss(num);
        if (flag == num) {
            printf("%d\n", num);
            break;
        }
        num++;
    }
    return 0;
}