#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for (int i = 0; i < (long long)(n); i++)
#define REP(i, n) for (int i = 1; i < (long long)(n); i++)
typedef long long ll;
//#pragma GCC target("avx512f")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
#define updiv(N,X) (N + X - 1) / X
#define l(n) n.begin(),n.end()

#define YesNo(Q) Q==1?cout<<"Yes":cout<<"No"
using P = pair<int, int>;
using mint = modint998244353;
const int MOD = 998244353LL;
const ll INF = 999999999999LL;
ll dvt(ll a,ll b){
    ll res=0;ll aa=a; 
    while(b<=aa){aa /= 2;res++;}
    return res;
}

int main() {
 ll a,b,c;cin>>a>>b>>c;cout << min((-1)*(a-1)*b-c,(a-1)*b-a*c) << endl;
}