#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> P;
typedef vector<ll> VI;
typedef vector<VI> VVI;
#define REP(i,n) for(ll i=0;i<(n);i++)
#define ALL(v) v.begin(),v.end()
constexpr ll MOD=1000000007;
constexpr ll INF=2e18;

int main(){
    ll d, a, b; cin >> d >> a >> b;
    ll ans=INF;
    REP(i,d+1){
        ans=min(ans,i*a+(d-i)*b);
    }
    cout << ans << endl;
}