#include <iostream>
#include <cstdio>
using namespace std;

/*
Add `int max_of_four(int a, int b, int c, int d)` here.
*/
int max_of_four(int a, int b, int c, int d)
{
    if(b > a) a = b ;
    if(d > c) c = d ;
    if(c > a) a = c ;
    
    return a ; 
}

int main() {
    int a, b, c, d;
    scanf("%d %d %d %d", &a, &b, &c, &d);
    int ans = max_of_four(a, b, c, d);
    printf("%d", ans);
    
    return 0;
}

Functions are a bunch of statements glued together. A function is provided with zero or more arguments, and it executes the statements on it. Based on the return type, it either returns nothing (void) or something.

The syntax for a function is

return_type function_name(argtype1 arg1, argtype2 arg2, ...) 
{
    ...
    ...
    ...
    [if returntype is non void]
      return something of type return_type;
}

For example, a function to return the sum of four parameters can be written as

int sum_of_four(int a, int b, int c, int d) 
{
    int sum = 0;
    sum += a;
    sum += b;
    sum += c;
    sum += d;
    return sum;
}

+= : Add and assignment operator. It adds the right operand to the left operand and assigns the result to the left operand.
a += b is equivalent to a = a + b;

Write a function int max_of_four(int a, int b, int c, int d) which returns the maximum of the four arguments it receives.

Input Format
Input will contain four integers a, b, c, d, one per line.

Output Format
Return the greatest of the four integers.
PS: I/O will be automatically handled.

Sample Input
3
4
6
5

Sample Output
6