C code to convert octal number to decimal number

#include<stdio.h>
#include<math.h>

int main(){
   
    long int octal,decimal =0;
    int i=0;

    printf("Enter any octal number: ");
    scanf("%ld",&octal);

    while(octal!=0){
         decimal = decimal + (octal % 10) * pow(8,i++);
         octal = octal/10;
    }

    printf("Equivalent decimal value: %ld",decimal);

   return 0;
}