#include <stdio.h>
#include <stdlib.h>

int gcd(long long a, long long b)
{
    return a % b == 0 ? b : gcd(b, a % b);
}

int main()
{
    int n;
    long long num[3000], b, sum;
    scanf("%d", &n);
    for (int i = 0; i < n; i++) scanf("%I64d", &num[i]);
    b = num[0];
    for (int i = 1; i < n; i++) {
        long long c = gcd(b, num[i]);
        b = b * num[i] / c;
    }
    sum = 0;
    for (int i = 0; i < n; i++) {
        sum += (b - 1) % num[i];
    }
    printf("%I64d\n", sum);
    return 0;
}
