n,m = map(int,input().split())
a = [list(map(int,input().split())) for i in range(n)]
INF = 10**18
if n == 1:print(0); exit()
dp = [[INF]*(m) for i in range(n)]
dp[-1] = a[-1][::1]
for i in range(n-1)[::-1]:
  mn = INF
  for j in range(m):
    dp[i][j] =  dp[i+1][j] + a[i][j]
    mn = min(mn,dp[i][j])
  for j in range(m):
    if dp[i][j] == mn: continue
    dp[i][j] = min(dp[i][j], mn + a[i][j])

print(min(dp[0]))