#include
int sum_of_even(int x);
int main()
{
int x=0,sum=0;
sum+=sum_of_even(x);
printf("%d",sum);
return 0;
}
int sum_of_even(int x)
{
int sum=0;
for(;x<=20;x+=2)
{
sum+=x;
}
return sum;
}