C :

#include<stdio.h>
int main(){
int a,b,c,max;
scanf("%d%d%d",&a,&b,&c);
max=a;
if(max<b)
  max=b;
else if(max<c)
  max=c;
printf("%d\n",max);
return 0;
}

C++ :

#include <stdio.h>
int main() {
	int max(int x, int y);
	int a, b, c, d;
	scanf("%d %d %d", &a, &b, &c);
	d = max(max(a, b), c);
	printf("%d\n", d);
	return 0;
}
int max(int x, int y) {
	int z;
	if (x > y) z = x;
	else z = y;
	return z;
}

Java :

import java.util.*;
public class Main {
	public static void main(String args[]) {
		Scanner cin = new Scanner(System.in);
		int[] i={0,0,0};
		i[0]=cin.nextInt();
		i[1]=cin.nextInt();
		i[2]=cin.nextInt();
		Arrays.sort(i);
		System.out.println(i[2]);
	}
}