# Write a python function to find sum of prime numbers between 1 to n.
def sum_Of_Primes(n):
    prime = [True] * (n + 1)
    p = 2
    while p * p <= n:
        if prime[p] == True:
            i = p * 2
            while i <= n:
                prime[i] = False
                i += p
        p += 1
    sum = 0
    for i in range(2, n + 1):
        if prime[i]:
            sum += i
    return sum
