int sum = 0;
for(int i = 1; i <= 10; ++i) {
    sum += i;
}
cout << sum;

int sum;
for(int i = 1; i <= 10; ++i) {
    sum += i;
}
cout << sum;

int sum = 0;
for(int i = 0; i < 10; ++i) {
    sum += i;
}
cout << sum;

int sum = 0;
int i = 1;
while(i <= 10) {
    sum += i;
}
cout << sum;