Buggy python submission (verdict: Time Limit Exceeded):
from sys import stdin,setrecursionlimit
from copy import deepcopy
import heapq

n,m = map(int,stdin.readline().rstrip().split())

li = [[0 for i in range(n+1)]for j in range(n+1)]

inf = 10**10

def all_pairs_shortest_paths(W):
    # 頂点の数
    n = len(W)
    # 結果を格納する行列を用意する
    res = [[0] * n for i in range(n)]
    # 用意した行列を初期化する
    for i in range(n):
        for j in range(i, n):
            if i == j:
                val = 0
            elif W[i][j]:
                val = W[i][j]
            else:
                val = inf
            res[i][j] = res[j][i] = val
    # 動的計画法ですべての超点間の最短距離を求める
    for k in range(n):
        for u in range(n):
            for v in range(n):
                res[u][v] = min(res[u][v], res[u][k] + res[k][v])
    return res

lin = [list(map(int,stdin.readline().rstrip().split())) for _ in range(m)]

true = [True]*(n+1)
point = 0

for j in range(m):
    lis = []
    for num,i in enumerate(lin):
        if num != j:
            lis.append(i)
    liv = [[0 for e in range(n+1)]for o in range(n+1)]
    for kp in lis:
        liv[kp[0]][kp[1]] = 1
        liv[kp[1]][kp[0]] = 1
    kota = all_pairs_shortest_paths(liv)[1:]
    flag = True
    for kk in kota:
        if inf in kk[1:]:
            flag = False
    if flag:
        point += 1

print(m-point)

Fixed submission:
from sys import stdin

inf = 10**3
n,m = [int(x) for x in stdin.readline().rstrip().split()]

li = [list(map(int,stdin.readline().rstrip().split())) for _ in range(m)]
nu = []

def warshall_floyd(d):
    #d[i][j]: iからjへの最短距離
    #k：中継
    for k in range(n):
        for i in range(n):
            for j in range(n):
                d[i][j] = min(d[i][j],d[i][k] + d[k][j])
    return d
point = 0
for i in range(m):
    d = [[inf for i in range(n)]for j in range(n)]
    lin = li[:i]+li[i+1:]
    for j in range(m-1):
        d[lin[j][0]-1][lin[j][1]-1] = 1
        d[lin[j][1]-1][lin[j][0]-1] = 1
    for k in range(n):
        d[k][k] = 0
    lis = warshall_floyd(d)
    for i in lis:
        if inf in i:
            point += 1
            break
print(point)

Buggy python submission (verdict: Time Limit Exceeded):
from sys import stdin
inf = 10**3
n,m = [int(x) for x in stdin.readline().rstrip().split()]
li = [list(map(int,stdin.readline().rstrip().split())) for _ in range(m)]
def warshall_floyd(d):
    for k in range(n):
        for i in range(n):
            for j in range(n):
                d[i][j] = min(d[i][j],d[i][k] + d[k][j])
    return d
point = 0
for i in range(m):
    d = [[inf for i in range(n)]for j in range(n)]
    lin = li[:i]+li[i+1:]
    for j in range(m-1):
        d[lin[j][0]-1][lin[j][1]-1] = 1
        d[lin[j][1]-1][lin[j][0]-1] = 1
    for k in range(n):
        d[k][k] = 0
    lis = warshall_floyd(d)
    for i in lis:
        i.sort()
        if i[-1] == inf:
            point += 1
            break
print(point)

Fixed submission:
from sys import stdin

inf = 10**3
n,m = [int(x) for x in stdin.readline().rstrip().split()]

li = [list(map(int,stdin.readline().rstrip().split())) for _ in range(m)]
nu = []

def warshall_floyd(d):
    #d[i][j]: iからjへの最短距離
    #k：中継
    for k in range(n):
        for i in range(n):
            for j in range(n):
                d[i][j] = min(d[i][j],d[i][k] + d[k][j])
    return d
point = 0
for i in range(m):
    d = [[inf for i in range(n)]for j in range(n)]
    lin = li[:i]+li[i+1:]
    for j in range(m-1):
        d[lin[j][0]-1][lin[j][1]-1] = 1
        d[lin[j][1]-1][lin[j][0]-1] = 1
    for k in range(n):
        d[k][k] = 0
    lis = warshall_floyd(d)
    for i in lis:
        if inf in i:
            point += 1
            break
print(point)

Buggy python submission (verdict: Runtime Error):
from sys import stdin
import math
import bisect
import heapq
import numpy as np
from math import factorial

inf = 10**3
n,m = [int(x) for x in stdin.readline().rstrip().split()]

li = [list(map(int,stdin.readline().rstrip().split())) for _ in range(m)]
nu = []

def warshall_floyd(d):
    #d[i][j]: iからjへの最短距離
    #k：中継
    for k in range(n):
        for i in range(n):
            for j in range(n):
                d[i][j] = min(d[i][j],d[i][k] + d[k][j])
    return d
point = 0
for i in range(m):
    d = [[inf for i in range(n)]for j in range(n)]
    lin = li[:i]+li[i+1:]
    for j in range(m-1):
        d[lin[j][0]-1][lin[j][1]-1] = 1
        d[lin[j][1]-1][lin[j][0]-1] = 1
    for k in range(n):
        d[k][k] = 0
    lis = warshall_floyd(d)
    for i in lis:
        if inf in i:
            point += 1
            break
print(point)

Fixed submission:
from sys import stdin

inf = 10**3
n,m = [int(x) for x in stdin.readline().rstrip().split()]

li = [list(map(int,stdin.readline().rstrip().split())) for _ in range(m)]
nu = []

def warshall_floyd(d):
    #d[i][j]: iからjへの最短距離
    #k：中継
    for k in range(n):
        for i in range(n):
            for j in range(n):
                d[i][j] = min(d[i][j],d[i][k] + d[k][j])
    return d
point = 0
for i in range(m):
    d = [[inf for i in range(n)]for j in range(n)]
    lin = li[:i]+li[i+1:]
    for j in range(m-1):
        d[lin[j][0]-1][lin[j][1]-1] = 1
        d[lin[j][1]-1][lin[j][0]-1] = 1
    for k in range(n):
        d[k][k] = 0
    lis = warshall_floyd(d)
    for i in lis:
        if inf in i:
            point += 1
            break
print(point)

Buggy python submission (verdict: Time Limit Exceeded):
from sys import stdin
import math
import bisect
import heapq
import numpy as np
from math import factorial

inf = 10**3
n,m = [int(x) for x in stdin.readline().rstrip().split()]

li = [list(map(int,stdin.readline().rstrip().split())) for _ in range(m)]
nu = []

def warshall_floyd(d):
    #d[i][j]: iからjへの最短距離
    #k：中継
    for k in range(n):
        for i in range(n):
            for j in range(n):
                d[i][j] = min(d[i][j],d[i][k] + d[k][j])
    return d
point = 0
for i in range(m):
    d = [[inf for i in range(n)]for j in range(n)]
    lin = li[:i]+li[i+1:]
    for j in range(m-1):
        d[lin[j][0]-1][lin[j][1]-1] = 1
        d[lin[j][1]-1][lin[j][0]-1] = 1
    for k in range(n):
        d[k][k] = 0
    lis = warshall_floyd(d)
    for i in lis:
        if inf in i:
            point += 1
            break
print(point)

Fixed submission:
from sys import stdin

inf = 10**3
n,m = [int(x) for x in stdin.readline().rstrip().split()]

li = [list(map(int,stdin.readline().rstrip().split())) for _ in range(m)]
nu = []

def warshall_floyd(d):
    #d[i][j]: iからjへの最短距離
    #k：中継
    for k in range(n):
        for i in range(n):
            for j in range(n):
                d[i][j] = min(d[i][j],d[i][k] + d[k][j])
    return d
point = 0
for i in range(m):
    d = [[inf for i in range(n)]for j in range(n)]
    lin = li[:i]+li[i+1:]
    for j in range(m-1):
        d[lin[j][0]-1][lin[j][1]-1] = 1
        d[lin[j][1]-1][lin[j][0]-1] = 1
    for k in range(n):
        d[k][k] = 0
    lis = warshall_floyd(d)
    for i in lis:
        if inf in i:
            point += 1
            break
print(point)