946C - String Transformation - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
#define mod 1000000007
#define double long double
#define INT_MIN -1000000000000000
#define INT_MAX 1e18


void solve()
{
    // Write your code here 
    string s;
    getline(cin,s);
    char c = 'a';
    for(int i=0;i<s.size();i++)
    {
        if(s[i]<=c)
        {
            s[i]=c;
            c+=1;
        }
        if(c>'z')
            break;
    }
    if(c>'z')
    {
        cout<<s<<endl;
        return;
    }
    cout<<-1<<endl;
}
signed main()
{
    int t=1;
    //cin>>t;

    while(t--)
    {
        solve();
    }
}