S=input()
o=0
i=0
for j in S:
    if j=="0":
        o+=1
    else:
        i+=1
print(min(o,i)*2) S=input() S input() input o=0 o 0 i=0 i 0 for j in S:
    if j=="0":
        o+=1
    else:
        i+=1 j S if j=="0":
        o+=1
    else:
        i+=1 j=="0" j "0" o+=1 o 1 i+=1 i 1 print(min(o,i)*2) print min(o,i)*2 min(o,i) min o i 2 S=input() input() S i+=1 1 i o+=1 1 o o=0 0 o i=0 0 i
S=input()
o=0
i=0
for j in S:
    if j=="0":
        o+=1
    else:
        i+=1
print(min(o,i)*2)