40pts求助，（样例调不出来……

#include<bits/stdc++.h>
using namespace std; 
int m,s,c,ans,a[210],b[210];
bool cmp(int a,int b){
    return a > b;
} int main(){ 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);
    ans = a[c] - a[1] + 1;
    for(int i = 1;i < c;i++){
    	b[i] = a[i + 1] - a[i];
	} sort(b + 1,b + c,cmp);
    for(int i = 1;i <= m - 1;i++) ans -= b[i];
    cout << ans; return 0;
}