1370_E. Binary Subsequence Rotation
Naman has two binary strings s and t of length n (a binary string is a string which only consists of the characters "0" and "1"). He wants to convert s into t using the following operation as few times as possible.

In one operation, he can choose any subsequence of s and rotate it clockwise once.

For example, if s = 1110100, he can choose a subsequence corresponding to indices (1-based) \{2, 6, 7 \} and rotate them clockwise. The resulting string would then be s = 1010110.

A string a is said to be a subsequence of string b if a can be obtained from b by deleting some characters without changing the ordering of the remaining characters.

To perform a clockwise rotation on a sequence c of size k is to perform an operation which sets c_1:=c_k, c_2:=c_1, c_3:=c_2, …, c_k:=c_{k-1} simultaneously.

Determine the minimum number of operations Naman has to perform to convert s into t or say that it is impossible. 

Input

The first line contains a single integer n (1 ≤ n ≤ 10^6) — the length of the strings.

The second line contains the binary string s of length n.

The third line contains the binary string t of length n.

Output

If it is impossible to convert s to t after any number of operations, print -1.

Otherwise, print the minimum number of operations required.

Examples

Input


6
010000
000001


Output


1

Input


10
1111100000
0000011111


Output


5

Input


8
10101010
01010101


Output


1

Input


10
1111100000
1111100001


Output


-1

Note

In the first test, Naman can choose the subsequence corresponding to indices \{2, 6\} and rotate it once to convert s into t.

In the second test, he can rotate the subsequence corresponding to all indices 5 times. It can be proved, that it is the minimum required number of operations.

In the last test, it is impossible to convert s into t.
```python
# -*- coding: utf-8 -*-
"""
@author: Saurav Sihag
"""

rr = lambda: input().strip()
# rri = lambda: int(rr())
rri = lambda: int(stdin.readline())
rrm = lambda: [int(x) for x in rr().split()]
# stdout.write(str()+'\n')

from sys import stdin, stdout

def sol():
    n=rri()
    s=rr()
    t=rr()
    cnt=0
    mn=0
    mx=0
    for i in range(n):
        if (s[i]=='1'):
            cnt+=1
        if (t[i]=='1'):
            cnt-=1
        mn=min(mn, cnt)
        mx=max(mx, cnt)
    if cnt!=0:
        print(-1)
    else:
        print(mx-mn)
    return

sol()
# T = rri()
# for t in range(1, T + 1):
#     ans = sol()
    # print("Case #{}: {}".format(t, ans))


```