import sequtils,strutils
var
    N = stdin.readline.parseInt
if N == 1:
    echo 1
else:
    var b = 100000
    while N > 1:
        b += 1
        var f = false
        for i in 2..1000:
            if b mod i == 0:
                f = true
                break
        if not f:
            N -= 1
            if N == 1:
                echo b