A：签到
#include<iostream> #include<cstdio> #include<cmath> #include<cstdlib> #include<cstring> #include<algorithm> using namespace std; int read() { int x=0,f=1;char c=getchar(); while (c<'0'||c>'9') {if (c=='-') f=-1;c=getchar();} while (c>='0'&&c<='9') x=(x<<1)+(x<<3)+(c^48),c=getchar(); return x*f; } #define N 1010 int n,a[N]; int main() { n=read(); for (int i=1;i<=n;i++) a[i]=read(); sort(a+1,a+n+1); cout<<a[n]-a[1]+1-n; return 0; }