import std;
void main(){
	auto input = readln.chomp.split(" ").to!(long[]);
	long N = input[0];
	long A = input[1];
	long B = input[2];
	if(2 * A > B){
		if(N % 2 == 0){
			if(A > B){
				writeln(A * (-1 * (N - 1)));
			}else{
				writeln(A * (-1 * (N - 2) + 1) - B * 2);
			}
		}else{
			writeln(A * (-1 * (N - 1)) - B);
		}
	}else{
		writeln(A * (N - 1) - B * N);
	}
}