Help me in solving LPYAS151 problem

help
,
1

My issue

what is error in the programe

My code

#include<bits/stdc++.h>
using namespace std;
int main (){
    int n;
    cin>>n;
    int original_number=n;
    int no_of_digits=0;
    while(n!=0){
        n=n/10;
        no_of_digits++;
        
    }
    n=original_number;
    int sum =0;
    while(n!=0){
    int last_digt=n%10;
    sum += pow(last_digit,no_of_digits);
    n=n/10;
    }
if(sum=original_number){
    cout<<"armstrong";
}
else cout<<"not armstrong";

}

Learning course: ATT - C++
Problem Link: https://www.codechef.com/learn/course/sit-att-cpp-new/SITCPP91A/problems/LPYAS151