http://codeforces.com/contest/426/problem/B

对称标题的意思大概是。应当指出的,当线数为奇数时,答案是线路本身的数

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxn 1005
using namespace std;

char a[maxn][maxn];
int ans;

void solve(int r)
{
if(r % 2)
return;

for(int i = 1, j = r; i <= r / 2; i ++, j --)
{
if(strcmp(a[i], a[j]))
return;
}

ans /= 2;
solve (r / 2);
}

int main()
{
int row, lie;

scanf("%d%d", &row, &lie);
getchar();

int i;
for(i = 1; i <= row; i ++)
{
gets(a[i]);
// cout << i << endl;
}

ans = row;
solve(row);

cout << ans << endl;
return 0;
}