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

n, m = list(map(int, input().rstrip().split()))
ans = [""] * m
arr = []
cnt = 1
for i in range(m):
    p, y = map(int, input().split())
    arr += [(p, y, i)]
arr = sorted(arr)

ans[arr[0][2]] = "{:06}{:06}".format(arr[0][0], cnt)
for i in range(1, m):
    if arr[i - 1][0] == arr[i][0]:
        cnt += 1
    else:
        cnt = 1
    ans[arr[i][2]] = "{:06}{:06}".format(arr[i][0], cnt)

for i in asn:
    print(i)

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

n, m = list(map(int, input().rstrip().split()))
ans = [""] * m
arr = []
cnt = 1
for i in range(m):
    p, y = map(int, input().split())
    arr += [(p, y, i)]
arr = sorted(arr)

ans[arr[0][2]] = "{:06}{:06}".format(arr[0][0], cnt)
for i in range(1, m):
    if arr[i - 1][0] == arr[i][0]:
        cnt += 1
    else:
        cnt = 1
    ans[arr[i][2]] = "{:06}{:06}".format(arr[i][0], cnt)

for i in ans:
    print(i)

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

n, m = list(map(int, input().rstrip().split()))
ans = [""] * m
arr = []
cnt = 1
for i in range(m):
    p, y = map(int, input().split())
    arr += [(p, y, i)]
arr = sorted(arr)

ans[arr[0][2]] = "{:06}{:06}".format(arr[0][0], cnt)
for i in range(1, m):
    if arr[i - 1][0] == arr[i][0]:
        cnt += 1
    else:
        cnt = 1
    ans[arr[i][2]] = "{:06}{:06}".format(arr[i][0], cnt)

for i in asn:
    print(i)
print(*ans, sep="\n")

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

n, m = list(map(int, input().rstrip().split()))
ans = [""] * m
arr = []
cnt = 1
for i in range(m):
    p, y = map(int, input().split())
    arr += [(p, y, i)]
arr = sorted(arr)

ans[arr[0][2]] = "{:06}{:06}".format(arr[0][0], cnt)
for i in range(1, m):
    if arr[i - 1][0] == arr[i][0]:
        cnt += 1
    else:
        cnt = 1
    ans[arr[i][2]] = "{:06}{:06}".format(arr[i][0], cnt)

for i in ans:
    print(i)

Buggy python submission (verdict: Time Limit Exceeded):
## ABC113C - ID
import sys
input = sys.stdin.readline

n, m = list(map(int, input().rstrip().split()))
arr = [list(map(int, input().rstrip().split())) for _ in range(m)]
pref = [[] for _ in range(n)]
for i in arr:
    pref[i[0] - 1] += [i]
pref = [sorted(i) for i in pref]
for i in arr:
    j = pref[i[0] - 1].index(i) + 1
    print("{:0>6}{:0>6}".format(i[0], j))

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

n, m = list(map(int, input().rstrip().split()))
ans = [""] * m
arr = []
cnt = 1
for i in range(m):
    p, y = map(int, input().split())
    arr += [(p, y, i)]
arr = sorted(arr)

ans[arr[0][2]] = "{:06}{:06}".format(arr[0][0], cnt)
for i in range(1, m):
    if arr[i - 1][0] == arr[i][0]:
        cnt += 1
    else:
        cnt = 1
    ans[arr[i][2]] = "{:06}{:06}".format(arr[i][0], cnt)

for i in ans:
    print(i)

Buggy python submission (verdict: Time Limit Exceeded):
## ABC113C - ID
import sys
input = sys.stdin.readline

n, m = list(map(int, input().rstrip().split()))
arr = [list(map(int, input().rstrip().split())) for _ in range(m)]
pref = [[] for _ in range(n)]
for i in arr:
    pref[i[0] - 1] += [i]
pref = [sorted(i) for i in pref]
for i in arr:
    j = pref[i[0] - 1].index(i) + 1
    print("{:0>6}{:0>6}".format(i[0], j))

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

n, m = list(map(int, input().rstrip().split()))
ans = [""] * m
arr = []
cnt = 1
for i in range(m):
    p, y = map(int, input().split())
    arr += [(p, y, i)]
arr = sorted(arr)

ans[arr[0][2]] = "{:06}{:06}".format(arr[0][0], cnt)
for i in range(1, m):
    if arr[i - 1][0] == arr[i][0]:
        cnt += 1
    else:
        cnt = 1
    ans[arr[i][2]] = "{:06}{:06}".format(arr[i][0], cnt)

for i in ans:
    print(i)