Varianta 1:
#include <iostream>
using namespace std;
int main() {
long long n, c, r, m;
cin >> n >> c >> r;
if(n % c >= r)
{
m = (n / c + 1) * c + r;
}
else
{
m = (n / c) * c + r;
}
cout << m;
return 0;
}
Varianta 2:
#include <iostream>
using namespace std;
int main() {
long long n, c, r, m;
cin >> n >> c >> r;
if(n % c >= r)
{
m = n + r - n % c + c;
}
else
{
m = n + r - n % c;
}
cout << m;
return 0;
}