Buggy python submission (verdict: Time Limit Exceeded):
from decimal import *

n = int(input())
ans = 0
vec = [Decimal(input()) for i in range(n)]
vec25 = [[0 for i in range(50)] for i in range(50)]  # 整数にするのに余っている2,5の数
for i in range(n):
    a = vec[i] * 1000000000
    num2 = -9
    num5 = -9
    while a%2 == 0:
        a //= 2
        num2 += 1
    while a%5 == 0:
        a //= 5
        num5 += 1
    vec25[num2][num5] += 1
for i in range(-9, 40): 
    for j in range(-9, 20):
        for k in range(max(-9, -i), 40):
            for l in range(max(-9, -j), 20):
                if i+k >= 0 and j+l >= 0 :
                    if i != k or j != l :
                        ans += vec25[i][j] * vec25[k][l]
                    else :
                        ans += vec25[i][j] * (vec25[i][j] - 1)
ans //= 2
print(ans)

Fixed submission:
from decimal import *

n = int(input())
ans = 0
vec = [Decimal(input()) for i in range(n)]
vec25 = [[0 for i in range(50)] for i in range(50)]  # 整数にするのに余っている2,5の数
for i in range(n):
    a = int(vec[i] * 1000000000)
    num2 = -9
    num5 = -9
    while a%2 == 0:
        a //= 2
        num2 += 1
    while a%5 == 0:
        a //= 5
        num5 += 1
    vec25[num2][num5] += 1
for i in range(-9, 40): 
    for j in range(-9, 20):
        for k in range(max(-9, -i), 40):
            for l in range(max(-9, -j), 20):
                if i+k >= 0 and j+l >= 0 :
                    if i != k or j != l :
                        ans += vec25[i][j] * vec25[k][l]
                    else :
                        ans += vec25[i][j] * (vec25[i][j] - 1)
ans //= 2
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from decimal import *


n = int(input())
ans = 0
vec = [Decimal(input()) for i in range(n)]
vec25 = [[-9, -9] for i in range(n)]  # 整数にするのに余っている2,5の数
for i in range(n):
    a = vec[i] * 1000000000
    while a%2 == 0:
        a //= 2
        vec25[i][0] += 1
    while a%5 == 0:
        a //= 5
        vec25[i][1] += 1
mp = {}
for p in vec25:
    k = p[0] * 10000 + p[1]
    if k in mp:
        mp[k] += 1
    else:
        mp[k] = 1
for k1, v1 in mp.items():
    x5 = k1 % 10000
    while x5 > 100:
        x5 -= 10000
    x2 = (k1 - x5) // 10000
    # print(k1, x2, x5)
    if x5 >= 0 and x2 >= 0:
        ans += v1 * (v1 - 1) // 2
    for k2, v2 in mp.items():
        y5 = k2 % 10000
        while y5 > 100:
            y5 -= 10000
        y2 = (k2 - y5) // 10000
        if x5 + y5 >= 0 and x2 + y2 >= 0 and k1 > k2:
            ans += v1 * v2
print(ans)

Fixed submission:
from decimal import *

n = int(input())
ans = 0
vec = [Decimal(input()) for i in range(n)]
vec25 = [[0 for i in range(50)] for i in range(50)]  # 整数にするのに余っている2,5の数
for i in range(n):
    a = int(vec[i] * 1000000000)
    num2 = -9
    num5 = -9
    while a%2 == 0:
        a //= 2
        num2 += 1
    while a%5 == 0:
        a //= 5
        num5 += 1
    vec25[num2][num5] += 1
for i in range(-9, 40): 
    for j in range(-9, 20):
        for k in range(max(-9, -i), 40):
            for l in range(max(-9, -j), 20):
                if i+k >= 0 and j+l >= 0 :
                    if i != k or j != l :
                        ans += vec25[i][j] * vec25[k][l]
                    else :
                        ans += vec25[i][j] * (vec25[i][j] - 1)
ans //= 2
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from decimal import *
import math


n = int(input())
ans = 0
vec = [Decimal(input()) for i in range(n)]
vec25 = [[-9, -9] for i in range(n)]  # 整数にするのに余っている2,5の数
for i in range(n):
    a = vec[i] * 1000000000
    while a%2 == 0:
        a //= 2
        vec25[i][0] += 1
    while a%5 == 0:
        a //= 5
        vec25[i][1] += 1
mp = {}
for p in vec25:
    k = p[0] * 10000 + p[1]
    if k in mp:
        mp[k] += 1
    else:
        mp[k] = 1
for k1, v1 in mp.items():
    x5 = k1 % 10000
    while x5 > 100:
        x5 -= 10000
    x2 = (k1 - x5) // 10000
    # print(k1, x2, x5)
    if x5 >= 0 and x2 >= 0:
        ans += v1 * (v1 - 1) // 2
    for k2, v2 in mp.items():
        y5 = k2 % 10000
        while y5 > 100:
            y5 -= 10000
        y2 = (k2 - y5) // 10000
        if x5 + y5 >= 0 and x2 + y2 >= 0 and k1 > k2:
            ans += v1 * v2
print(ans)

Fixed submission:
from decimal import *

n = int(input())
ans = 0
vec = [Decimal(input()) for i in range(n)]
vec25 = [[0 for i in range(50)] for i in range(50)]  # 整数にするのに余っている2,5の数
for i in range(n):
    a = int(vec[i] * 1000000000)
    num2 = -9
    num5 = -9
    while a%2 == 0:
        a //= 2
        num2 += 1
    while a%5 == 0:
        a //= 5
        num5 += 1
    vec25[num2][num5] += 1
for i in range(-9, 40): 
    for j in range(-9, 20):
        for k in range(max(-9, -i), 40):
            for l in range(max(-9, -j), 20):
                if i+k >= 0 and j+l >= 0 :
                    if i != k or j != l :
                        ans += vec25[i][j] * vec25[k][l]
                    else :
                        ans += vec25[i][j] * (vec25[i][j] - 1)
ans //= 2
print(ans)