math.abs是错的

#include<iostream>
#include<math.h>
using namespace std;
int main()
{
    int a,b,c;
    cin>>a>>b>>c;
    int m = (a + b + abs(a-b)) / 2;
    cout<<(c + m + abs(c-m)) / 2<<" eh o maior";
    return 0;
}