#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int n,sum=-999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999; cin>>n; int a[n+1]; for(int i=1;i<=n;i++){ cin>>a[i]; } for(int i=1;i<=n;i++){ for(int j=2;j<=n;j++){ if(i>j){ sum=i-j; } } } cout<<sum-1; return 0; }