C monkey eat peach

C monkey eat peach
The monkey has a peach problem. On the first day, the monkey picked several peaches and immediately ate half of them. They were so addicted that they ate another one. The next morning, I ate another half of the remaining peaches, and I ate another one. In the future, the remaining half of the previous day will be eaten every day, and one peach will be left when you want to eat it again on the morning of the seventh day. How many peaches can be picked on the first day. Code implementation:

# Include <stdio. h> int sum_peach (const int n, int sum) {int I = 0; for (I = n; I> 0; I --) {sum = 2 * sum + 1;} return sum;} int main () {int n = 0; int sum = 0; printf ("Enter the number of days :"); scanf ("% d", & n); sum = sum_peach (n, sum); printf ("% d \ n", sum); return 0 ;}