为什么会CE

#include<iostream>
#include<set>
#include<cstdio>
#include<string>
#include<cstdlib>
using namespace std;

set <string> a;
string std_out,tmp;

void output(){
	cout << std_out;
}

int main(){
	int n,shayongmeiyou;
	char *num;
	cin >> n;
	for(int i = 1;i<=n;i++){
		cin >> tmp;
		if(!a.count(tmp)){
			a.insert(tmp);
			std_out = "OK";
			output();
		}else {
		    string add;
			float j = 1;
			while(true){
				num = fcvt(j,0,&shayongmeiyou,&shayongmeiyou);
				add = tmp + *num;
                if(a.count(add)){
                    j += 1;
                    continue;
                }else {
                    a.insert(add);
                    std_out = add;
                    output();
                    break;
                }
			}
		}
	}
	return 0;
}