Description The numbers of all offices in the new building of the Tax Office of IT City will have lucky numbers. Lucky number is a number that consists of digits 7 and 8 only. Find the maximum number of offices in the new building of the Tax Office given that a door-plate can hold a number not longer than n digits. Input The only line of input contains one integer n (1 ≤ n ≤ 55) — the maximum length of a number that a door-plate can hold. Output Output one integer — the maximum number of offices, than can have unique lucky numbers not longer than n digits. Sample Input
Input
2
Output
6
<span style="font-size:12px;color:#000000;">#include <stdio.h>
#include <math.h>
int main()
{
long long n;
while (scanf("%lld", &n) != EOF) {
long long ans = 2;
if (n == 0) continue;
for (long long i = 2; i <= n; i++) {
ans = ans + pow(2 , i);
}
printf("%lld
", ans);
}
return 0;
}
</span> |