#include<bits/stdc++.h> using namespace std; int main() { char a,b,s; cin>>a>>b>>s; int t=a-'0'; int v=s-'0'; cout<<t*v; return 0; }

#include<bits/stdc++.h>
using namespace std;
int main()
{   
    int a1,a2,n;
    cin>>a1>>a2>>n;
    int b=a2-a1;
    int an=a1+(n-1)*b;
    cout<<setw(3)<<an;
    return 0;
}