циклы, найти суммы всех целых чисел от 100 до 500 на с++

#include
using namespace std;
int main() {
long sum, max = 500, min = 100, start;
sum = 0;
start = max;
while (start >= min) sum += start--;
cout << " 1 var: sum = " << sum << endl;
sum = 0;
start = max;
do sum += start; while (--start >= min);
cout << " 2 var: sum = " << sum << endl;
sum = 0;
for (start = min; start <= max; ++start) sum += start;
cout << " 3 var: sum = " << sum << endl;
sum = 0;
for (start = max; start >= min; --start) sum += start;
cout << " 4 var: sum = " << sum << endl;
cin.get();
return 0;
}