let inpt = Int(readLine()!)!

var primeList = [1]
var flags = [Bool](repeating: false, count: inpt + 101)
for i in 2...inpt + 100 {
    if(flags[i]) {
        continue
    }
    for j in 1...(inpt+100)/i {
        flags[i*j] = true
    }
    primeList.append(i)
}

for i in inpt - 100 ... inpt + 100 {
    if(!primeList.contains(i)) {
        print(i)
        break
    }
}