Convert Numbers According to Base

#include<stdio.h>
#include<math.h>
int main()
{
    int base, bin, oct, dec, hex, d, r, i;
    printf("Enter Base: ");
I:
    scanf("%d",&base);
    if(base!=2 && base!=8 && base!=10 && base!=16) //INVALID
    {
        printf("Error!!! Invalid Base!\n\nThe Base Should be: \n2 for Binary. or \n8 for Octal. or \n10 for Decimal or.\n16 for Hexadecimal\n\nEnter The Base Again: ");
        goto I;
    }
    else if(base==2) //BINARY
    {
        printf("Enter The Binary Number: ");
        scanf("%d",&bin);
        dec=0, i=0;
        while(bin!=0)
        {
            r=bin%10;
            bin=bin/10;
            dec=dec+(r*pow(2,i));
            i++;
        }
        printf("The Corresponding Octal Value is: %o\n",dec);
        printf("The Corresponding Decimal Value is: %d\n",dec);
        printf("The Corresponding HexaDecimal Value is: %x\n",dec);

    }
    else if(base==8) //OCTAL
    {
        printf("Enter The Octal Number: ");
        scanf("%o",&oct);
        dec=oct, i=1, bin=0;
        while(dec!=0)
        {
            r=dec%2;
            dec/=2;
            bin+=r*i;
            i*=10;
        }
        printf("The Corresponding Binary Value is: %d\n",bin);
        printf("The Corresponding Decimal Value is: %d\n",oct);
        printf("The Corresponding Hexadecimal Value is: %x\n",oct);
    }
    else if(base==10) //DECIMAL
    {
        printf("Enter The Decimal Number: ");
        scanf("%d",&dec);
        d=dec, i=1, bin=0;
        while(d!=0)
        {
            r=d%2;
            d/=2;
            bin+=r*i;
            i*=10;
        }
        printf("The Corresponding Binary Value is: %d\n",bin);
        printf("The Corresponding Octal Value is: %o\n",dec);
        printf("The Corresponding HexaDecimal Value is: %x\n",dec);
    }
    else if(base==16) //HEXADECIMAL
    {
        printf("Enter The Hexadecimal Number: ");
        scanf("%x",&hex);
        dec=hex, i=1, bin=0;
        while(dec!=0)
        {
            r=dec%2;
            dec/=2;
            bin+=r*i;
            i*=10;
        }
        printf("The Corresponding Binary Value is: %d\n",bin);
        printf("The Corresponding Octal Value is: %o\n",hex);
        printf("The Corresponding Decimal Value is: %d\n",hex);
    }
    return 0;
}