#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int a1; cin>>a1; int a2; cin>>a2; int n; cin>>n; cout<<(a2-a1)*n<<endl; return 0; }