L1-017 到底有多二

#include <iostream>
#include <algorithm>
#include <cmath>
#include <map>
#include <cstdio>
#include <sstream>
#include <cstring>
#include <cctype>

using namespace std;
#define maxn 3000

int main()
{
    string s; cin >>s;
    float ans = 0;
    int flag =1;
    if(s[0]== ‘-‘) flag =0;
    for(int i= s.size()-1;i>=0;i--)
        if((s[i]-48)==2) ans++;
    if(flag)
        ans = ans/s.size();
    else 
        ans = (ans/(s.size()-1))*1.5;
    if((s[s.size()-1]-48 )%2 ==0 ) ans *=2;
    printf("%.2f%%",ans*100);
    return 0;
}