Problem p03252 (python)

Fixed submission:
#!/usr/bin/env python3
from collections import defaultdict
from collections import deque
from heapq import heappush, heappop
import sys
import math
import bisect
import random
import itertools
sys.setrecursionlimit(10**5)
stdin = sys.stdin
bisect_left = bisect.bisect_left
bisect_right = bisect.bisect_right
def LI(): return list(map(int, stdin.readline().split()))
def LF(): return list(map(float, stdin.readline().split()))
def LI_(): return list(map(lambda x: int(x)-1, stdin.readline().split()))
def II(): return int(stdin.readline())
def IF(): return float(stdin.readline())
def LS(): return list(map(list, stdin.readline().split()))
def S(): return list(stdin.readline().rstrip())
def IR(n): return [II() for _ in range(n)]
def LIR(n): return [LI() for _ in range(n)]
def FR(n): return [IF() for _ in range(n)]
def LFR(n): return [LI() for _ in range(n)]
def LIR_(n): return [LI_() for _ in range(n)]
def SR(n): return [S() for _ in range(n)]
def LSR(n): return [LS() for _ in range(n)]
mod = 1000000007
inf = float('INF')

#A
def A():
    a = LI()
    a.sort()
    a, b, c = a
    print(int(str(c)+str(b))+a)
    return

#B
def B():
    _, _, X, Y = LI()
    x = LI()
    y = LI()
    x.append(X)
    y.append(Y)
    x.sort()
    y.sort()
    print("No " * (x[-1] < y[0]) + "War")
    return

#C
def C():
    s = S()
    t = S()
    ds = defaultdict(int)
    dt = defaultdict(int)
    for i in range(len(s)):
        if ds[s[i]]:
            if ds[s[i]] == ord(t[i]):
                continue
            print("No")
            return
        if dt[t[i]]:
            if dt[t[i]] == ord(s[i]):
                continue
            print("No")
            return
        ds[s[i]] = ord(t[i])
        dt[t[i]] = ord(s[i])
    print("Yes")
    return

#D
def D():
    return

#Solve
if __name__ == '__main__':
    C()

Buggy submission (verdict: Runtime Error):
#!usr/bin/env python3
from collections import defaultdict
from collections import deque
from heapq import heappush, heappop
import sys
import math
import bisect
import random
import itertools
sys.setrecursionlimit(10**5)
stdin = sys.stdin
def LI(): return list(map(int, stdin.readline().split()))
def LF(): return list(map(float, stdin.readline().split()))
def LI_(): return list(map(lambda x: int(x)-1, stdin.readline().split()))
def II(): return int(stdin.readline())
def IF(): return float(stdin.readline())
def LS(): return list(map(list, stdin.readline().split()))
def S(): return list(stdin.readline().rstrip())
def IR(n): return [II() for _ in range(n)]
def LIR(n): return [LI() for _ in range(n)]
def FR(n): return [IF() for _ in range(n)]
def LFR(n): return [LI() for _ in range(n)]
def LIR_(n): return [LI_() for _ in range(n)]
def SR(n): return [S() for _ in range(n)]
def LSR(n): return [LS() for _ in range(n)]
mod = 1000000007

#A
def A():
    n = II()
    print("ABC"+str(n))
    return

#B
def B():
    ni = [2 ** i for i in range(1, 10)]
    n = II()
    ans = 1
    for i in range(1, n + 1):
        if i in ni:
            ans = i
    print(ans)        
    return

#C
def C():
    alp = [chr(ord('a') + i) for i in range(26)]
    s = S()
    t = S()
    ss = [[] for i in range(26)]
    for i in range(len(s)):
        ss[alp.index(s[i])].append(t[i])
        ss[alp.index(s[i])] = set(ss[alp.index(s[i])])
    for st in ss:
        if len(st) >= 2:
            print("Yes")
            return
    print("No")
    return

#D
def D():
    return

#E
def E():
    return

#F
def F():
    return

#G
def G():
    return

#H
def H():
    return

#Solve
if __name__ == '__main__':
    C()