n = int(input "Nhap so:")
d = 0
x = 2

while d < n :
    flag = true
    for i in range (2,x)
        if x % i == 0
            flag = false
    if flag == true
        d = d + 1
        if d == n
            break
    x = x + 1
print ( "so nguyen to thu" + str(n) + "la" + str(x))