INF = float('inf')
N, M = map(int, input().split())
if N == 1:
    exit(print(0))
A = [list(map(int, input().split())) for _ in range(N)]

dp = [0] * M
for i in range(N):
    ndp = [dp[j] + A[i][j] for j in range(M)]
    m = min(ndp)
    nndp = [min(ndp[j], m + A[i][j]) for j in range(M)]
    dp = nndp

print(min(dp))