C :

#include<stdio.h>
int main(){
int a,b;
double x,y;
scanf("%d %d %lf %lf",&a,&b,&x,&y);
printf("%.6lf\n",(float)(a+b)/2+(int)x%(int)y);
return 0;
}

C++ :

#include <stdio.h>
int main() {
	float x, y, ans;
	int a, b;
	scanf("%d %d %f %f", &a, &b, &x, &y);
	ans = (float)(a + b) / 2 + (int)x % (int)y;
	printf("%.6f\n", ans);
	return 0;
}

Java :

import java.util.*;
public class Main {
	public static void main(String args[]) {
		Scanner cin = new Scanner(System.in);
		double x,y;
		int a,b;
		a=cin.nextInt();
		b=cin.nextInt();
		x=cin.nextDouble();
		y=cin.nextDouble();
		double r = (float)(a+b)/2+(int)x%(int)y;
		System.out.printf("%.6f",r);
	}
}