#include<iostream>
#include<string>
#include<cmath>
#include<cstdlib>
using namespace std;

int main()
{
    string chislo, ex;
    int length, i, k, chisl[100];
    double p, sum(0);
    do
    {
        cout<<"Input data to convert into DEC system!"<<endl<<"Input p: ";
        do
        {
            cin>>p;
             p=static_cast<int>(p);
              if ((p>16) || (p<2))
                  {
                      cerr<<"Error 'p' is bigger than 16, or less than 2!!!"<<endl;
                      cout<<"Input p: ";
                  }
        } while(p>16 || p<2);
        cin.ignore(100, '\n');
        cout<<"Input number: ";
        getline(cin, chislo);
        length=chislo.length();

for (i=0; i<=(length-1); i++)
{
          chisl[i]=static_cast<int>(chislo[i])-static_cast<int>('0');
          if (chisl[i]==49)
           {
               chisl[i]=10;
           }
           else if (chisl[i]==50)
           {
               chisl[i]=11;
           }
           else if (chisl[i]==51)
           {
               chisl[i]=12;
           }
           else if (chisl[i]==52)
           {
               chisl[i]=13;
          }
           else if (chisl[i]==53)
           {
               chisl[i]=14;
           }
           else if (chisl[i]==54)
           {
               chisl[i]=15;
           }
           if (!((chisl[i]>=0)&&(chisl[i]<=15)))
           {
               cerr<<"Error, incorrect data!";
               exit(1);
           }
             chisl[i]++;
             cout<<chisl[i]<<endl;
             chislo[i]++;
}

        for (i=0, k=(length-1);k>=0, i<=(length-1);k--, i++)
        {

           sum+=chisl[i]*pow(p,k);

        }

        cout<<"result: "<<sum<<endl<<endl<<"Input 'exit' to quit, or any key to continue: ";
        sum=0;
        cin>>ex;
        cout<<endl;
     cout<<static_cast<int>('a')-static_cast<int>('0')<<endl; //проверка, выдает 49
     cout<<static_cast<int>('1')-static_cast<int>('0'); //выдает 1
     }while(ex!="exit");

return 0;
}

for (i=0; i<=(length-1); i++)
{
          chisl[i]=static_cast<int>(chislo[i])-static_cast<int>('0');
          if (chisl[i]==49)
           {
               chisl[i]=10;
           }
           else if (chisl[i]==50)
           {
               chisl[i]=11;
           }
           else if (chisl[i]==51)
           {
               chisl[i]=12;
           }
           else if (chisl[i]==52)
           {
               chisl[i]=13;
          }
           else if (chisl[i]==53)
           {
               chisl[i]=14;
           }
           else if (chisl[i]==54)
           {
               chisl[i]=15;
           }
           if (!((chisl[i]>=0)&&(chisl[i]<=15)))
           {
               cerr<<"Error, incorrect data!";
               exit(1);
           }
             chisl[i]++;
             cout<<chisl[i]<<endl;
             chislo[i]++;
}

 for (i=0, k=(length-1);k>=0, i<=(length-1);k--, i++)
        {

           sum+=(static_cast<int>chisl[i]-static_cast<int>('0'))*pow(p,k);

        }