where i make mistake

#include <iostream.h>

int main(){
int n,q;
cin>>n;
if (n==0)
{q=10;
         cout<<q;
         goto tu;}
if(n<100);
{
          for(int x=1;x<10;x++)
{
          for(int y=1;y<10;y++)
{
          q=x*y;
          if(q==n)
          {cout<<x<<y;
          goto tu;
          }}}}

          if((n>=100) && (n<1000))
          {
                     for(int x=1;x<10;x++)
                     {for(int y=1;y<10;y++)
                     {for(int o=1;o<10;o++)
                    { q=x*y*o;
          if(q==n)
          {cout<<x<<y<<o;
          goto tu;
          }}}}}
          if((n>=1000) && (n<10000))
          {for(int x=1;x<10;x++)
                     {for(int y=1;y<10;y++)
                     {for(int o=1;o<10;o++)
                     {for(int a=1;a<10;a++)
                     {
                        q=x*y*o*a;
          if(q==n)
          {cout<<x<<y<<o<<a;
          goto tu;
          }}}}}}
          if((n>=10000) && (n<100000))
          {for(int x=1;x<10;x++)
                     {for(int y=1;y<10;y++)
                     {for(int o=1;o<10;o++)
                     {for(int a=1;a<10;a++)
                     {for(int b=1;b<0;b++)
                     {
                        q=x*y*o*a*b;
          if(q==n)
          {cout<<x<<y<<o<<a<<b;
          goto tu;
          }}}}}}}
          if((n>=100000) && (n<1000000))
          {for(int x=1;x<10;x++)
                     {for(int y=1;y<10;y++)
                     {for(int o=1;o<10;o++)
                     {for(int a=1;a<10;a++)
                     {for(int b=1;b<0;b++)
                     {for(int c=1;c<10;c++)
                     {
                        q=x*y*o*a*b*c;
          if(q==n)
          {cout<<x<<y<<o<<a<<b<<c;
          goto tu;
          }}}}}}}}
               if((n>=1000000) && (n<10000000))
          {for(int x=1;x<10;x++)
                     {for(int y=1;y<10;y++)
                     {for(int o=1;o<10;o++)
                     {for(int a=1;a<10;a++)
                     {for(int b=1;b<0;b++)
                     {for(int c=1;c<10;c++)
                     {for(int d=1;d<10;d++)
                     {
                        q=x*y*o*a*b*c*d;
          if(q==n)
          {cout<<x<<y<<o<<a<<b<<c<<d;
          goto tu;
          }}}}}}}}}
                         if((n>=10000000) && (n<100000000))
          {for(int x=1;x<10;x++)
                     {for(int y=1;y<10;y++)
                     {for(int o=1;o<10;o++)
                     {for(int a=1;a<10;a++)
                     {for(int b=1;b<0;b++)
                     {for(int c=1;c<10;c++)
                     {for(int d=1;d<10;d++)
                     {for(int e=1;e<10;e++)
                     {
                        q=x*y*o*a*b*c*d*e;
          if(q==n)
          {cout<<x<<y<<o<<a<<b<<c<<d<<e;
          goto tu;
          }}}}}}}}}}
          cout<<-1;
          tu: ;
          system("pause");
          return 0;
          }

Your program goes wrong for this test case
1000000000.The output is 555555555888
Your Output is -1.