题解

#include<iostream>
#include<algorithm>
using namespace std;
int a[205];
int s1[205];
int cmp(int p,int q){
	return p > q;
}
int main(){
	int m,s,c;
	cin >> m >> s >> c;
	if(m>=c) {
		cout << c;
		return 0;
	}
	for(int i=1;i<=c;i++){
		cin >> a[i];
	}
	sort(a+1,a+c+1);
	for(int i=1;i<c;i++){
		s1[i] = a[i+1]-a[i];
	}
	sort(s1+1,s1+c,cmp);
	int sum = a[c]-a[1] + m;
	for(int i=1;i<m;i++){
		sum -= s1[i];
	}
	cout << sum;
	return 0;
}