def su2(k,l):
    a=k+l
    if a>9:
        r=a%10
        a=1+r
    return a
T=int(input())
S=[list(input()) for i in range (T)]
#rint(S)
for i in range(T):
    for j in range(len(S[i])):
        S[i][j]=int(S[i][j])
   #     print (S)
    j=len(S[i])
  #  print (j)
    while j > 2:
        for k in range(1,len(S[i])-j-1):
            S[i][k-1]=su2(S[i][k-1], S[i][k])
        j-=1
    S[i][0]=su2(S[i][0],S[i][1])
print(S[i][0])