Language: C++

#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define REP(i,n) for(int i=0;i<n;i++)
#define REPP(i,n) for(int i=1;i<=n;i++)
#define ALL(obj) (obj).begin(), (obj).end()
const double PI = acos(-1);
const double EPS = 1e-15;
long long INF=(long long)1E17;
#define i_7 (long long)(1E9+7)
long mod(long a){
    long long c=a%i_7;
    if(c>=0)return c;
    return c+i_7;
}
using namespace std;

long long po(long long a, long long b, long long m){
    if(b==0){
        return 1;
    }
    
    long long z = po(a,b/2);
    z = (z*z)%m;
    if(b%2!=0){
        z = (a*z)%m;
    }
    return z;
}

bool prime_(int n){
  if(n==1){
    return false;
  }else if(n==2){
    return true;
  }else{
    for(int i=2;i<=sqrt(n);i++){
      if(n%i==0){
        return false;
      }
    }
    return true;
  }
}

long long gcd_(long long a, long long b){
  if(a<b){
    swap(a,b);
  }
  if(a%b==0){
    return b;
  }else{
    return gcd_(b,a%b);
  }
}
 
long long lcm_(long long x, long long y){
  return (x/gcd_(x,y))*y;
}

int main(){
  
  long long l,a,b,m;
  cin>>l>>a>>b>>m;
  long long c;
  long long power = 1;
  long long ans[3];
  ans[0] = 0;
  ans[1] = a%m;
  ans[2] = 1LL;
  for(int d = 1; d<=18; d++){
    long long left, right;
    left = (power - a)/b;
    left = max(left, -1);
    right = (10*power - a)/b;
    right = min(right, l-1);
    c = right - left;
    power *= 10;
    long long mat[3][3] = {};
    mat[0][0] = po(10LL, d, m);
    mat[1][0] = mat[1][1] = mat[2][2] = 1LL;
    mat[2][1] = b%m;
    while(c>0){
      if(c & 1){
        long long temp[3] = {};
        REP(i,3){
          REP(j,3){
            temp[i] += (ans[j]*mat[j][i])%m;
            temp[i] %= m;
          }
        }
        REP(i,3){
          ans[i] = temp[i];
        }
      }
      c /= 2;
      
      long long tempMat[3][3] = {};
      REP(i,3){
        REP(j,3){
          REP(k,3){
            tempMat[i][j] += mat[i][k]*mat[k][j];
            tempMat[i][j] %= m;
          }
        }
      }
      REP(i,3){
        REP(j,3){
          mat[i][j] = tempMat[i][j];
        }
      }
    }
  }
  
  cout<<ans[0]<<endl;
  return 0;
}


Compiler output:
a.cc: In function 'long long int po(long long int, long long int, long long int)':
a.cc:22:21: error: too few arguments to function 'long long int po(long long int, long long int, long long int)'
   22 |     long long z = po(a,b/2);
      |                   ~~^~~~~~~
a.cc:17:11: note: declared here
   17 | long long po(long long a, long long b, long long m){
      |           ^~
a.cc: In function 'int main()':
a.cc:73:15: error: no matching function for call to 'max(long long int&, int)'
   73 |     left = max(left, -1);
      |            ~~~^~~~~~~~~~
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:73:15: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'int')
   73 |     left = max(left, -1);
      |            ~~~^~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:73:15: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   73 |     left = max(left, -1);
      |            ~~~^~~~~~~~~~