感觉写的很对啊wa的理由是啥？

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
#define PII pair<int,int>
#define tul tuple<int,int,int>
#define all(x) x.begin(),x.end()
#define cy cout<<"Yes"<<endl
#define cn cout<<"No"<<endl
#define lc rt<<1
#define rc rt<<1|1
const int N=3e5+6,yyx=998244353;
int n,m,a[N],p[N];
inline void solve(){
  cin>>n;
  string s,t="";cin>>s;
  map<char,char> mp;
  mp['R']='P';mp['P']='S';mp['S']='R';
  for(int i=0;i<n;++i){
    char ch=mp[s[i]];
    if(ch==t[i-1]&&i) ch=s[i];
    t+=ch;
  }
  int ans=0;
  for(int i=0;i<n;++i) if(t[i]==mp[s[i]]) ans++;
  cout<<ans<<endl;
}
signed main(){
  cin.tie(0)->sync_with_stdio(0);
  //freopen("D://321//in.txt","r",stdin);
  //freopen("D://321//out.txt","w",stdout);
  int _=1;
  //cin>>_;
  while(_--)
  solve();
  return 0;
}