C-10 age issues

Problem B: Age issues
Time Limit: 1 Sec Memory Limit: 64 MB
Submit: 12725 Solved: 8524
Description
Yes n A person sits together , Ask No n How old is an individual ？ He said bidi n-1 Personal big m year . Ask No n-1 Personal age , He said bidi n-2 Personal big m year . Ask No n-2 personal , And he said bidi n-3 National People's Congress m year .… Finally, ask the first person , He says it is K year . May I ask n How old are you ？ （ Recursive function implementation ）
Input
Multiple sets of test data Each group has one row. Input separately 3 It's an integer n, m and k
Output
Output No n Personal age
Sample Input
5 2 10
Sample Output
18

#include <stdio.h>
int age(int n,int m,int k);

int main()
{
    
	int n,m,k;
	while (scanf("%d%d%d",&n,&m,&k) != EOF)
	{
    
		printf("%d\n",age(n,m,k));
	}
	return 0;
}
// Recursive conditions ： Please n Personal age  = n-1 Personal age +m
// Up to recursive condition ： The first 1 An individual's age is k year , return k
int age(int n,int m,int k)
{
    
	int sum = 0;
	if (n == 1)
		return k;
	else 
		sum += age(n-1,m,k) + m;
	return sum; 
}

Do recursive questions , To find the recursive core expression ！
Find the return value or condition up to recursion ！