#include<iostream>
using namespace std;
int main()
{
	int a,b,c;
	cout<<"a="; cin>>a;
	cout<<"b="; cin>>b;
	cout<<"c="; cin>>c;
	if(a>=b && a>=c) cout<<a;
    else if(b>=a && b>=c) cout<<b;
         else if(c>=a && c>=b) cout<<c;
    return 0;	
}

sau 

#include<iostream>
using namespace std;
int main()
{
	int a,b,c,max;
	cout<<"a="; cin>>a;
	cout<<"b="; cin>>b;
	cout<<"c="; cin>>c;
	max=a;
	if(b>max) max=b;
	if(c>max) max=c;
	cout<<max;
	return 0;
}