C :

#include<stdio.h>
#include<string.h>
int main()
{
    char a[10],i=0;
    while(~scanf("%s",a))
    {
            i++;
        if(!strcmp(a,"I"))
           printf("Case %d: 1\n",i);
        else if(!strcmp(a,"II"))
                printf("Case %d: 2\n",i);
        else if(!strcmp(a,"III"))
                printf("Case %d: 3\n",i);
        else if(!strcmp(a,"IV"))
                printf("Case %d: 4\n",i);
        else if(!strcmp(a,"V"))
                printf("Case %d: 5\n",i);
        else if(!strcmp(a,"VI"))
                printf("Case %d: 6\n",i);
        else if(!strcmp(a,"VII"))
                printf("Case %d: 7\n",i);
        else if(!strcmp(a,"VIII"))
                printf("Case %d: 8\n",i);
        else if(!strcmp(a,"IX"))
                printf("Case %d: 9\n",i);
        else if(!strcmp(a,"X"))
            printf("Case %d: 10\n",i);
        else if(!strcmp(a,"XI"))
            printf("Case %d: 11\n",i);
        else if(!strcmp(a,"XII"))
            printf("Case %d: 12\n",i);
    }
    return 0;
}

C++ :

#include<iostream>
#include<stdio.h>
#include<string>
using namespace std;
int main()
{ int n=0,k;
string a;
while(cin>>a)
{
printf("Case %d: ",++n);
if(a=="I")cout<<1<<endl;
else if(a=="II")cout<<2<<endl;
else if(a=="III")cout<<3<<endl;
else if(a=="IV")cout<<4<<endl;
else if(a=="V")cout<<5<<endl;
else if(a=="VI")cout<<6<<endl;
else if(a=="VII")cout<<7<<endl;
else if(a=="VIII")cout<<8<<endl;
else if(a=="IX")cout<<9<<endl;
else if(a=="X")cout<<10<<endl;
else if(a=="XI")cout<<11<<endl;
else cout<<12<<endl;
}
return 0;
}