Codeforces Round #288, Anton and currency you all know

Problem: Anton and currency you all know

///     Raihan Ruhin
///     CSE, Jahangirnagar University.
///     Dhaka-Bangladesh.
///     id: raihanruhin (topcoder / codeforces / codechef / hackerrank), 3235 (lightoj)
///     mail: raihanruhin@ (yahoo / gmail / facebook)
///     blog: ruhinraihan.blogspot.com

#include<bits/stdc++.h>
using namespace std;

#define SET(a) memset(a,-1,sizeof(a))
#define CLR(a) memset(a,0,sizeof(a))
#define PI acos(-1.0)

#define MOD 1000000007
#define MX 100010


int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);
    int tc,kk=1, n;
    string s;
    cin>>s;
    int st=-1;
    int sl=s.size();
    for(int i=0;i<sl-1;i++)
        if((s[i]-'0')%2==0 && (s[sl-1]-'0')>(s[i]-'0'))
        {
            swap(s[i], s[sl-1]);
            st=i;
            break;
        }
    if(st==-1)
    {
        for(int i=sl-2;i>=0;i--)
            if((s[i]-'0')%2==0 && s[i]!=s[sl-1])
            {
                swap(s[i], s[sl-1]);
                st=i;
                break;
            }
    }

    if(st==-1) cout<<"-1\n";
    else cout<<s<<"\n";
    return 0;
}