求助，不知道哪写挂了

#include <bits/stdc++.h>
#define int long long
using namespace std;
int base[104];
bool add(int x){
	for (int i=60;i>=0;i--){
		if (x&(1ll<<i)){
			if (!base[i]){
				base[i]=x;return 1;
			}else x^=base[x];
		}
	}
	return 0;
}
signed main(){
	int n,m;
	cin>>n>>m;
	int ans=1;
	for (int i=1;i<=m;i++){
		string s;cin>>s;
		int x=0;
		for (int j=0;j<n;j++){
			int p=n-1-j;
			if (s[j]=='O') x^=(1ll<<p);
		}
		if (add(x)) ans<<=1;
	} 
	cout<<ans%2008;
	return 0;
}