i=input
n=int(i())
m=int(i())
A=[list(map(int, i().split())) for _ in '1'*m]
B=[0]*m
for _ in range(n-1):
    new_B = [0]*m
    for j in range(m):
        new_B[j] = max([B[k]+A[k][j] for k in range(m)])
    B = new_B
print(max(new_B))