C++ evaluator

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

int velicina (int b)
{
double c;
for (int i=b;i>=1;i--)
{
c=b/i;
if (int(c)==c && i<=c) return i;
}
}
int main (void)
{
string n;
cin >> n;
int b;
b=n.size();
int r,c;
r=velicina(b);
c=b/r;
int k=0;
char p[r][c];
for (int i=0;i<c;i++)
{
for (int j=0;j<r;j++)
{
p[j][i]=n[k];
k++;
}
}
for (int i=0;i<r;i++)
{
for (int j=0;j<c;j++)
{
cout << p[i][j];
}
}

return 0;
}

Any suggestions why I got wrong results?