下面程序的运行结果是什么？

#include<iostream>

using namespace std;

int add(int x,int y){return x+y;}

int main( )

{int m=2,n=3;

cout<<"1:"<<add(m++,m+n)<<endl;

m=2,n=3;

cout<<"2:"<<add(++m,m+n)<<endl;

m=2,n=3;

cout<<"3:"<<endl;

m=2,n=3;

cout<<"4:"<<endl;

return 0;

}