CSTRING C++

#include<bits/stdc++.h>
using namespace std;

string s;
int n,c;
string ss = "";

string f(int n,string s)
{
    string s1="";
    for(int i=n;i<=s.length()-1;i++)
        s1=s1+s[i];
    s1=s1+s;
    return s1;
}

void giai()
{
    for(int i=1;i<=c;i++)
    {
        s=f(n,s);
    }
    cout<<s;
}
int main()
{
    freopen("CSTRING.inp","r",stdin);
    freopen("CSTRING.out","w",stdout);
    cin >> n >> c;
    cin >> s;
    giai();
}