CF158C Cd and pwd commands

#include<iostream>
#include<cstring>
using namespace std;
int main(){
    int n,j,k;
    string s,a="/",sum;
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        cin>>s;
        if(s=="cd"){
            cin>>s;
            s+='/';
            for(j=0;j<s.length();j++){
                sum+=s[j];
                if(s[j]=='/'){
                    if(sum=="/")
                        a=sum;
                    else if(sum=="../"){
                        for(k=a.length()-1;a[k-1]!='/';k--);
                        a.resize(k);
                    }
                    else
                        a+=sum;
                    sum="";
                }
            }
        }
        else
            cout<<a<<endl;
    }
    return 0;
}