请问大佬们哪错了```

#include<iostream>
using namespace std;
bool su(int a){ 
	for(int b=2;b<a;b++){
		if(a%b==0){
			return false;
		}
	}
	return true;
}

int main(){
    int a;
    cin>>a;
    int c=2,b;
    for(int i=4;i<=a;i+=2){
        while(c<i){
    	b=i-c;
    	if(su(c)==true&&su(b)==true){
    	    if(b<c){
    		    cout<<i<<"="<<b<<"+"<<c<<endl;
		    }else{
		        cout<<i<<"="<<c<<"+"<<b<<endl;
		    }
		    break;
	    }
        c++;	
	}
    }
    
	return 0;
}