Segmentation Fault possibly due to Iterator

This is my code. Upon running I get the segmentation fault and I guess it possibly due to the iterator "it" not getting a valid value.

for(it=v.begin();it!=v.end();it++)
        {

                for(it1=v.begin();it1!=v.end();it1++)
                {
                    if(*it>*it1 && *it<=*it1+k)
                    {
                       v.erase(it1);
                       it1=it1+1;
                    }
                }
        }

How can I correct it or if is it even possible to correct it or not