Submission #857502

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
long long n,s;
long long check(long long b,long long n){
     long long ans=0;
     while(n!=0){
        ans+=n%b;
        n/=b;
     }
     return ans;
}
int main(){
	cin>>n>>s;
		     //cout<<n<<s;

	long long ans=-1;
	REP(i,sqrt(n)+1){
	    if(i==0||i==1)continue;
		       //cout<<i<<" "<<check(i,n)<<endl;
	    if(check(i,n)==s){
	       ans=i;
	       break;
	    }
	}
        if(ans==-1&&s==n)ans=n+1;
        if(ans==-1){
           long long temp=n-s;
           REP(i,sqrt(temp)+2){
               if(i==0)continue;
               if(temp%i==0){
                  long long b=i+1;
                  long long a=n%b;
                  long long t=temp/i;

                  if(a+t==s){
                     if(b!=1){
                        ans=b;
                        break;
                     }
                  }
                  b=temp/i+1;
                  a=n%(b);
                  t=i;
                  //if(i<10){
                  //   cout<<i<<" "<<b<<" "<<temp<<endl;
                  //}

                  if(a+t==s){
                     if(b!=1){
                        ans=b;
                        break;
                     }
                  }
               }
           }
        }
        cout<<ans<<endl;
	return(0);
}

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