int arr[] = {5,3,10,3};

int n = 4;

float kmin = (float)(INT_MIN);

float kmax = (float)(INT_MAX);

bool flag = true;

for(int i=0;i<n-1;i++){

if(arr[i]>=arr[i+1]){//arr[i] - arr[i+1] > 0

kmin = max(kmin,(arr[i]+arr[i+1])/2.0);

}else{

kmax = min(kmax,(arr[i]+arr[i+1])/2.0);

}

if(kmax<kmin){

flag = false;

break;

}

}

if(flag == false) cout<<-1;

else if(kmax==kmin){

if(kmin-int(kmin)>0){//kmin and kmax are integers

cout<<"There is only one value of k: "<<kmin<<endl;

}

else{

cout<<-1;

}

}

else{

if(kmin-int(kmin)>0){

kmin = (int)kmin+1;

}

cout<<kmin<<" "<<(int)kmax;

}

return 0;

}