Buggy python submission (verdict: Time Limit Exceeded):
a = input()
b = input()
c = input()

la = len(a)
lb = len(b)
lc = len(c)

AB = [False]*la
AC = [False]*la
BA = [False]*lb
BC = [False]*lb
CA = [False]*lc
CB = [False]*lc
for i in range(la):
    for s,t in zip(a[i:],b):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        AB[i] = True
for i in range(la):
    for s,t in zip(a[i:],c):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        AC[i] = True
for i in range(lb):
    for s,t in zip(b[i:],a):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        BA[i] = True
for i in range(lb):
    for s,t in zip(b[i:],c):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        BC[i] = True
for i in range(lc):
    for s,t in zip(c[i:],a):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        CA[i] = True
for i in range(lc):
    for s,t in zip(c[i:],b):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        CB[i] = True

ans = la+lb+lc
for i in range(-(lb+lc),la+max(lb,lc)+1):
    for j in range(-(lb+lc),la+max(lb,lc)+1):
        if 0<=i<la:
            ab = AB[i]
        elif -lb<i<0:
            ab = BA[-i]
        else:
            ab = True
        
        if 0<=j<la:
            ac = AC[j]
        elif -lc<j<0:
            ac = CA[-j]
        else:
            ac = True
            
        k = j-i
        if 0<=k<lb:
            bc = BC[k]
        elif -lc<k<0:
            bc = CB[-k]
        else:
            bc = True
        
        if ab and ac and bc:
            l = min(0,i,j)
            r = max(la,i+lb,j+lc)
            ans = min(ans,r-l)
print(ans)

Fixed submission:
a = input()
b = input()
c = input()

la = len(a)
lb = len(b)
lc = len(c)

AB = [False]*la
AC = [False]*la
BA = [False]*lb
BC = [False]*lb
CA = [False]*lc
CB = [False]*lc
for i in range(la):
    for s,t in zip(a[i:],b):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        AB[i] = True
for i in range(la):
    for s,t in zip(a[i:],c):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        AC[i] = True
for i in range(lb):
    for s,t in zip(b[i:],a):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        BA[i] = True
for i in range(lb):
    for s,t in zip(b[i:],c):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        BC[i] = True
for i in range(lc):
    for s,t in zip(c[i:],a):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        CA[i] = True
for i in range(lc):
    for s,t in zip(c[i:],b):
        if not(s=='?' or t=='?' or s==t):
            break
    else:
        CB[i] = True

ans = la+lb+lc
for i in range(-(lb+lc),la+max(lb,lc)+1):
    if 0<=i<la:
        ab = AB[i]
    elif -lb<i<0:
        ab = BA[-i]
    else:
        ab = True
    if not ab: continue
    l = min(0,i)
    r = max(la,i+lb)
    if ans <= r-l : continue
    for j in range(-(lb+lc),la+max(lb,lc)+1):
        
        
        if 0<=j<la:
            ac = AC[j]
        elif -lc<j<0:
            ac = CA[-j]
        else:
            ac = True
            
        k = j-i
        if 0<=k<lb:
            bc = BC[k]
        elif -lc<k<0:
            bc = CB[-k]
        else:
            bc = True
        
        if ab and ac and bc:
            l = min(0,i,j)
            r = max(la,i+lb,j+lc)
            ans = min(ans,r-l)
print(ans)