import sys
input = sys.stdin.readline

def bellmanford(s):
    N = (c+1)*m
    dist = [10**18]*N
    dist[s] = 0
    
    for i in range(N-1):
        for s, t, w in edges:
            if dist[t]>dist[s]+w:
                dist[t] = dist[s]+w

    return min(dist)

n = int(input())-1
m = int(input())
A = [list(map(int, input().split())) for _ in range(m)]
dp = [[[0]*m for _ in range(m)] for _ in range(40)]

for i in range(m):
    for j in range(m):
        dp[0][i][j] = A[i][j]

for i in range(1, 40):
    for j in range(m):
        for k in range(m):
            for l in range(m):
                dp[i][j][k] = max(dp[i][j][k], dp[i-1][j][l]+dp[i-1][l][k])

edges = []
c = 0

for i in range(40):
    if (n>>i)&1:
        for j in range(m):
            for k in range(m):
                edges.append((c*m+j, (c+1)*m+k, -dp[i][j][k]))
                
        c += 1

wrong_answer = 0

for i in range(m):
    wrong_answer = max(wrong_answer, -bellmanford(i))

print(wrong_answer)