N=int(input())
A,B=[],[]
for i in range(N-1):
  x,y=map(int, input().split())
  A.append(x)
  B.append(y)
ans=10**12
a,b=sum(A),sum(B)
ans=min(a,b)+1
for i in range(N-1):
  da,db=a-A[i],b-B[i]
  ans=min(ans,da+db+1)
print(ans)