A - Even But Not Even

1291A - Even But Not Even
签到题，一开始用了很复杂的方法找奇数来删，但是wa了很多发之后发觉
只要找俩奇数搭在一起就行了，0全删掉就ok

#include<bits/stdc++.h>
#define lson (o<<1)
#define rson (o<<1|1)
#define fi first
#define sc second
#define dbg(x) cout<<#x<<" = "<<(x)<<endl;
#define rg register
typedef long long ll;
typedef unsigned int uint;
typedef unsigned long long ull;
using namespace std;
const double pi=acos(-1);
const double eps=1e-6;
inline int lowbit(int x){return x&(-x);}

template<typename A,typename B,typename C> inline A fpow(A x,B p,C yql){
	A ans=1;
	for(;p;p>>=1,x=1LL*x*x%yql)if(p&1)ans=1LL*x*ans%yql;
	return ans;
}

inline int read()
{
    int X=0,w=1;
    char c=getchar();
    while(c<'0'||c>'9')
    {
        if (c=='-')
        {
            w=-1;
        }
        c=getchar();
    }
    while(c>='0'&&c<='9')
    {
        X=(X<<3)+(X<<1)+(c^48);
        c=getchar();
    }
    return X*w;
}
//inline void w(int x) { if(x>9) w(x/10); putchar(x%10+'0'); }
char s[3005];
int ans[3005];
int main(){
	std::ios::sync_with_stdio(0);
	int t,len;
	cin>>t;
	while(t--){
		int cnt=0;
		cin>>len>>s;
		for(int i=0;i<len;i++){
			if(s[i]%2==1){
				ans[cnt++]=s[i]-'0';
			}
		}
		if(cnt<2){
			cout<<"-1"<<endl;
		}else {
			cout<<ans[0]<<ans[1]<<endl;
		}
	}
	return 0;
}