src.cpp:3:18: error: 'N' was not declared in this scope
long long int a[N],k,n,d,s,res;
^
src.cpp: In function 'long long int tknp(long long int)':
src.cpp:13:12: error: 'a' was not declared in this scope
if(a[giua]==k)
^
src.cpp: In function 'int main()':
src.cpp:30:32: error: 'a' was not declared in this scope
for(int i=1;i<=n;i++) cin>>a[i];
^