n, m = map(int, input().split())
if n == 1:
    print(0)
    exit()
dp = list(map(int, input().split()))
for _ in range(n - 1):
    A = list(map(int, input().split()))
    mi = min(a + d for a, d in zip(A, dp))
    for i in range(m):
        dp[i] = min(dp[i] + A[i], mi + A[i])
print(min(dp))