#include<iostream>
#include<string>
using namespace std;
int sa[550],sb[550],sc[550],sa1,sb1,sc1;
int mian(){
	string a,b;
	cin>>a>>b;
	for(int i=0;i<a.size();i++){
		sa[i]=a[i]-48;
	}
	for(int i=0;i<b.size();i++){
		sb[i]=b[i]-48;
	}
	sc1=max(a.size(),b.size());
	for(int i=0;i<sc1;i++){
		sc[i]+=(sb[i]+sa[i])%10;
		sc[i+1]+=(sb[i]-sa[i])/10; 
	}
	if(sc[sc1]>0) sc1++;
	for(int i=0;i<sc1;i++){
		cout<<sc[i];
	}
} 

最后输出了18 C:\crossdev\src\mingw-w64-v3-git\mingw-w64-crt\crt\crt0_c.c undefined reference to `WinMain@16'

C:\Users\Administrator\Documents\collect2.exe [Error] ld returned 1 exit status