def main():
    n, m, k = list(map(int, input().split()))
    node = [[] for _ in range(n)]
    for _ in range(m):
        u, v, w = list(map(int, input().split()))
        node[u-1].append((v-1, w%k))
        node[v-1].append((u-1, w%k))
    dp = [[0 for _ in range(k)] for _ in range(n)]
    dp[0][0] = 1
    A = [(0, 0)]
    while A:
        now, t = A.pop()
        for nxt, w in node[now]:
            nt = (t+w)%k
            if not dp[nxt][nt]:
                dp[nxt][nt] = 1
                A.append((nxt, nt))
    return dp[-1].index(1)
print(main())