Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.buffer.readline


def main():
    mod = 10**10
    N, M, L = map(int, input().split())
    dist = [[float('inf') for _ in range(N+1)] for _ in range(N+1)]
    ans = [[float('inf') for _ in range(N+1)] for _ in range(N+1)]
    for i in range(1, N+1):
        dist[i][i] = 0
        ans[i][i] = 0
    for _ in range(M):
        a, b, c = map(int, input().split())
        if c <= L:
            dist[a][b] = c
            dist[b][a] = c

    for i in range(1, N+1):
        for j in range(1, N+1):
            for k in range(1, N+1):
                dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j])
    for i in range(1, N+1):
        for j in range(N+1):
            if dist[i][j] <= L and i != j:
                ans[i][j] = 1
    for i in range(1, N+1):
        for j in range(1, N+1):
            for k in range(1, N+1):
                ans[i][j] = min(ans[i][j], ans[i][k] + ans[k][j])

    Q = int(input())
    for _ in range(Q):
        s, t = map(int, input().split())
        print(ans[s][t]-1) if ans[s][t] < 10**10 else print(-1)


if __name__ == '__main__':
    main()
import sys
input = sys.stdin.buffer.readline


def main():
    mod = 10**10
    N, M, L = map(int, input().split())
    dist = [[float('inf') for _ in range(N+1)] for _ in range(N+1)]
    ans = [[float('inf') for _ in range(N+1)] for _ in range(N+1)]
    for i in range(1, N+1):
        dist[i][i] = 0
        ans[i][i] = 0
    for _ in range(M):
        a, b, c = map(int, input().split())
        if c <= L:
            dist[a][b] = c
            dist[b][a] = c

    for i in range(1, N+1):
        for j in range(1, N+1):
            for k in range(1, N+1):
                dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j])
    for i in range(1, N+1):
        for j in range(N+1):
            if dist[i][j] <= L and i != j:
                ans[i][j] = 1
    for i in range(1, N+1):
        for j in range(1, N+1):
            for k in range(1, N+1):
                ans[i][j] = min(ans[i][j], ans[i][k] + ans[k][j])

    Q = int(input())
    for _ in range(Q):
        s, t = map(int, input().split())
        print(ans[s][t]-1) if ans[s][t] < 10**10 else print(-1)


if __name__ == '__main__':
    main()


Fixed submission:
import sys
input = sys.stdin.buffer.readline


def main():
    N, M, L = map(int, input().split())
    dist = [[float('inf') for _ in range(N+1)] for _ in range(N+1)]
    ans = [[float('inf') for _ in range(N+1)] for _ in range(N+1)]
    for i in range(1, N+1):
        dist[i][i] = 0
    for _ in range(M):
        a, b, c = map(int, input().split())
        if c <= L:
            dist[a][b] = c
            dist[b][a] = c

    for k in range(1, N+1):
        for j in range(1, N+1):
            for i in range(1, N+1):
                dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j])
    for i in range(1, N+1):
        for j in range(1, N+1):
            if dist[i][j] <= L:
                ans[i][j] = 1
    for k in range(1, N+1):
        for j in range(1, N+1):
            for i in range(1, N+1):
                ans[i][j] = min(ans[i][j], ans[i][k] + ans[k][j])

    Q = int(input())
    for _ in range(Q):
        s, t = map(int, input().split())
        if ans[s][t] < 10**10:
            print(ans[s][t]-1)
        else:
            print(-1)


if __name__ == '__main__':
    main()