#include<bits/stdc++.h>
using namespace std;
int main(){
    string s;
    cin>>s;
    int n;
    cin>>n;
    char a,b;
    int c,d;


    for(int i =0;i<s.size();i++){
            a = s[0];

        if(s[i]=='+'&& s[i+1]=='.'){
            b = s[i-1];
        }
    }
    c = a - '0';
    d = b - '0';
    int sum =c;
    int r = d-c;
    for(int i = 1;i<n;i++){
        sum = sum+d;
        d = d+r;

    }

    cout<<sum<<endl;



}