#include<iostream.h>
#include<string.h>
int main()
{
        int flag=0,i=0,j=0;
        char ar[4]="abc" ;
        char temp[4];
        cout<<"Plz enter a string with size #3";
        cin>>temp;
for(j=0;ar[j];j++)
        {
                flag=0;
                for(i=0;temp[i];i++)
                {
                        if(ar[j]==temp[i])
                                flag+=1;
                }
                if(flag==0||flag>1)
                        break;
        }
        if(flag==0||flag>1)
                cout<<"Not accepted";
        else
		cout<<"Accepted";
}
Note:PLz convert "iostream.h" into "stdio.h" and "cout<<" 
to "printf"