def notPrime(num):
    for i in range(2,(num)):
        if num % i == 0:
            return True
    return False



def maxPathSum(pyramid, m, n):
    for i in range(m-1, -1, -1):
        for j in range(i+1):
            if (pyramid[i+1][j] > pyramid[i+1][j+1]):
                pyramid[i][j] += pyramid[i+1][j]
            else:
                pyramid[i][j] += pyramid[i+1][j+1]
 
    return pyramid[0][0]


file = open("test.txt","r")
pyramid = []
count = 0
while True:
    data = file.readline().split()
    if not data:
        file.close()
        break
    pyramid.append(data)
for row in pyramid:
    for i in range(len(row)):
        row[i] = int(row[i])
for row in pyramid:    
    for num in range(len(pyramid[-1])-len(row)):
        row.append(0)

for i in range(len(pyramid)):
    for j in range(len(pyramid)):
        if pyramid[i][j] == 0:
            continue
        if not notPrime(pyramid[i][j]):
            pyramid[i][j] = 0
len_row = len(pyramid)
len_col = len(pyramid[0])
print(maxPathSum(pyramid,len_row-1,len_col-1))