need help in the following c++

1. A group of volunteers have offered to assist in planting trees for the Green campaign. There are 5000 trees to be planted. Plan and code a program to accept the number of trees taken by each volunteer. The program should stop when there are less than 1000 trees left. 2. Write a program that asks user to enter integers the loop will terminate if the user enters negative number or else it will print the number entered. 3. Write a program that reads a set of integers and then prints the sum of all even numbers