import math

x = 2
y = x
z = 1
test = 0

while x < 1001:
    while y < (int) math.sqrt(x):
        if x%y == 0:
            test = 1
            break
    if test == 0:
        print ('%d  --  %d', z, x)
        z += 1
    x +=1
    test = 0