sadly i dont know UML that well. maybe someone else knows

#include<stdio.h>

int addByValue(int a,int b){
    return a+b;
}
void subtractByReference(int*a,int*b){
    *a=*a-*b;
}
int main(){
    int num1,num2,result;

    printf("Enter the first number:");
    scanf("%d",&num1);
    printf("Enter the second number:");
    scanf("%d",&num2);

    result=addByValue(&num1,&num2);
    printf("Result of addition(by value):%d\n",result);
    result=subtractByRefernce(&num1,&num2);
    printf("Result of subtraction(by reference):%d\n",result);

    return 0;

}