//ignore header files
int main(int argc, char const* argv[])
{
    int x;
    while(scanf("%d",&x) != EOF){
        string line;
        getline(cin,line);
        getline(cin,line);
        istringstream stream(line);
        int an;
        int n = 0;
        int sum = 0;
        while(stream>>an){
            n++;
        }
        n--;
        istringstream s2(line);
        while(n>0){
            s2>>an;
            sum = sum*x;
            sum = sum+n*an;
            n--;
        }


        printf("%d\n",sum);

    }

    return 0;
}