太简单了

#include <iostream>
using namespace std;
int main(){int a, b, c;
    cin >> a >> b >> c;
    cout << max(a, max(b, c));
}

#include<iostream>
using namespace std;
int main(){
    int a,b,c;
    cin>>a>>b>>c;
    if(a>b&&a>c){
        cout<<a;
    }
    if(b>a&&b>c){
        cout<<b;
    }
    if(c>b&&c>a){
        cout<<c;
    }
}

C :

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

C++ :

#include<iostream>
using namespace std;
int main()
{
int a,b,c;
cin>>a>>b>>c;
if(a>b&&a>c)
cout<<a;
if(b>a&&b>c)
cout<<b;
if(c>b&&c>a)
cout<<c;
}