codeforce - Diverse Garland

#include<bits/stdc++.h>
using namespace std;
#define fastread()(ios_base::sync_with_stdio(false),cin.tie(NULL));
#define ll long long
int main()
{
    fastread()
    int n,i,r=0;
    string s;
    cin>>n>>s;
    i=1;
    while(i<n-1)
    {
        if(s[i]==s[i-1])
        {
            r++;

            if(s[i-1]=='G')
            {
                s[i]='B';
                if(s[i]==s[i+1])s[i]='R';
            }
            if(s[i-1]=='B')
            {
                s[i]='R';
                if(s[i]==s[i+1])s[i]='G';
            }
            if(s[i-1]=='R')
            {
                s[i]='G';
                if(s[i]==s[i+1])s[i]='B';
            }
        }
        i++;
    }
    if(s[i]==s[i-1])
        {
            r++;

            if(s[i-1]=='G')
            {
                s[i]='B';

            }
            if(s[i-1]=='B')
            {
                s[i]='R';

            }
            if(s[i-1]=='R')
            {
                s[i]='B';

            }
        }
        cout<<r<<endl<<s<<endl;
        return 0;
}