1787

#include <cstdio>

int main () {
    int k, n;
    int array[100];
    scanf("%d%d", &k, &n);
    for (int i=1; i<=100; i++){
        scanf ("%d", &array[i]);
    }
    int sum=0;
    for (int i=1; i<=100; i++) {
        sum+=array[i];
        }
    printf("%d", sum-(n*k));
    return 0;
}