n, m = map(int, input().split()) dp = list(map(int, input().split())) pa = dp[:] if n == 1: print(0) exit() for _ in range(n - 1): a = list(map(int, input().split())) mn = min(dp) dp = [min(dp[j] + a[j], mn + pa[j] + a[j]) for j in range(m)] pa = a print(min(dp))