C :

#include<stdio.h>
 
 
int main() {
    int a, n;
    long sum = 0;
    scanf("%d,%d", &a, &n);
    int m = a;
    int i ;
    for (i= 0; i < n ; ++i) {
        sum += m;
        m = m*10+a;
    }
    printf("sum=%ld\n", sum);
}