用flag来调节奇数和偶数
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<vector>
#include<map>
#define MAXN 200010
int n,m1,m2,ans,nn;
char a[MAXN],tmp[MAXN];
using namespace std;
inline bool check()
{
if(nn<=1) return true;
for(int i=1;i<nn;i+=2)
{
if(a[i]==a[i+1]) return false;
}
return true;
}
inline void solve()
{
int cnt=0;
int flag=0;
for(int i=1;i<=nn;i++,flag^=1)
{
if(i!=nn&&flag==0)
{
if(a[i]==a[i+1])
{
ans++;
flag^=1;
continue;
}
}
tmp[++cnt]=a[i];
}
nn=cnt;
for(int i=1;i<=nn;i++) a[i]=tmp[i];
// printf("nn=%d\n",nn);
}
int main()
{
#ifndef ONLINE_JUDGE
freopen("ce.in","r",stdin);
#endif
scanf("%d",&n);
scanf("%s",a+1);
nn=n;
if(check())
{
cout<<0<<endl;
for(int i=1;i<=n;i++) cout<<a[i];
cout<<endl;
return 0;
}
while(check()==false)
solve();
if(nn&1) ans++,nn--;
cout<<ans<<endl;
for(int i=1;i<=nn;i++) cout<<a[i];
cout<<endl;
return 0;
}