Language: C++

#include<stdio.h>
#include<cmath>
#include<math.h>
#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<complex>
#include<queue>
#include<set>
#include<utility>
#include<climits>
#include<iomanip>
#include<limits>
#include<thread>
#include<map>
#include<stack>
#include<numeric>
#include<cstring>
#include<cassert>
#include<random>
#include<chrono>
#include<unordered_set>
#include<unordered_map>
#include<fstream>
#include<list>
#include<functional>
#include<bitset>
#include<tuple>
#include <cstdio>
using namespace std;

#define pb          push_back
#define mp          make_pair
#define ll          long long int
#define hmap        unordered_map
#define pii         pair<int,int>
#define pdd         pair<double, double>
#define M           1000000007
#define MOD         998244353
#define fast        ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define test        ll t; cin>>t; while(t--)
#define inp(a,n)    int a[n]; for(int i=0;i<n;i++)  cin>>a[i];
#define inpl(a,n)   ll a[n];  for(ll i=0;i<n;i++)   cin>>a[i];
#define out(a,n)    for(int i=0;i<n;i++) cout<<a[i]<<" "; cout<<endl;
#define outl(a,n)   for(ll i=0;i<n;i++)  cout<<a[i]<<" "; cout<<endl;
#define outv(v)     for(int i=0;i<v.size();i++) cout<<v[i]<<" ";  cout<<endl;
#define all(s)      (s).begin(),(s).end()

#define rep(i,n) for(int i=0; i<n; i++)
#define rep1(i,n) for(int i=1; i<n+1; i++)
#define repr(i,n) for(int i=n-1; i>=0; i--)
#define repr1(i,n) for(int i=n; i>0; i--)
#define FOR(i,j,n) for(int i=j; i < n; i++)
#define souatari(i,j,n) rep1(i,n-1)rep(j,i)
#define souatari1(i,j,n) for(int i=2; i<n+1; i++)rep1(j,i-1)
#define mp make_pair
#define F first
#define S second
#define elif else if
#define inpv(a,n)   vector<int>a(n);  for(ll i=0;i<n;i++)   cin>>a[i];



ll  efficient_expo(ll a , ll  b , ll mod) {
	ll res = 1 ;
	// a = a % mod;
	// b = b % mod ;
	while (b > 0) {
		if (b & 1) res = (res * a) % mod ;
		a = (a * a) % mod ;
		b = b >> 1 ;
	}
	return res ;
}

int modd(int a, int b, int c)
{
	if (b == 0) return 1;

	if (b % 2 == 0)
	{
		int x = modd(a, b / 2, c);
		return (x * x) % c;
	}
	else return (a % c * modd(a, b - 1, c)) % c;
}

ll recursive_mod(ll a , ll b , ll mod) {
	if (b == 0) return 1 ;
	if (b & 1) return (a % mod * recursive_mod(a, b - 1, mod)) % mod;
	ll x = (recursive_mod(a, b / 2, mod)) ;
	return ((x ) * (x )) % mod ;
}

ll leading_digit(ll a , ll b ,ll k) {
	long long double  pro = b*log10(a) ; 
	long long double deci = pro - floor(pro) ;
	int po = pow(10,k-1);
	return (ll)(((long long double)pow(10,deci))*po) ;
}

ll trailing_digits(ll a, ll b, ll k){
	ll res = 1 ;
	while()
}

int main() {
// #ifndef ONLINE_JUDGE
// 	freopen("input.txt", "r", stdin);
// 	freopen("output.txt", "w", stdout);
// #endif
	fast ;
//     test{
        
//     }
    int a, int b ;
    cin >> a >> b ;
    cout << a*b ;
    
    

}


Compiler output:
a.cc: In function 'long long int leading_digit(long long int, long long int, long long int)':
a.cc:97:14: error: 'long long' specified with 'double'
   97 |         long long double  pro = b*log10(a) ;
      |              ^~~~
a.cc:98:14: error: 'long long' specified with 'double'
   98 |         long long double deci = pro - floor(pro) ;
      |              ^~~~
a.cc:100:28: error: 'long long' specified with 'double'
  100 |         return (ll)(((long long double)pow(10,deci))*po) ;
      |                            ^~~~
a.cc: In function 'long long int trailing_digits(long long int, long long int, long long int)':
a.cc:105:15: error: expected primary-expression before ')' token
  105 |         while()
      |               ^
a.cc:106:1: error: expected primary-expression before '}' token
  106 | }
      | ^
a.cc:106:1: warning: no return statement in function returning non-void [-Wreturn-type]
a.cc: In function 'int main()':
a.cc:117:12: error: expected unqualified-id before 'int'
  117 |     int a, int b ;
      |            ^~~
a.cc:118:17: error: 'b' was not declared in this scope
  118 |     cin >> a >> b ;
      |                 ^