#include <bits/stdc++.h>

using namespace std;
#define rep(i, n, o) for(int i = 0;i < (n);i++)
#define ou(x) cout << x << endl
#define ll long long
#define re return 0

int main(){
   int d, a, b;
   ll ans = 100010100010;
   cin >> d;
   cin >> a >> b;
   rep(i, d, 0){
        if(a == 0 || b == 0){
            ou(0);
            re;
        }
        ll t = i * a + (d - i) * b;
        ans = min(ans, t);
   }
   ou(ans);
    re;
}