#The Biggest Water Problem#
The Biggest Water Problem
https://www.nowcoder.com/practice/435aa556e093463891f6da7d322140a4
#include <stdio.h>
int main() {
int n;
scanf("%d", &n);
while (n > 9) {
int sum=0;
while (n) {
sum += n % 10;
n /= 10;
}
n=sum;
}
printf("%d\n",n);
return 0;
}
