Language: C++

#include<iostream>
#include<cstdio>
using namespace std;
int main(){
	int a[100][100],b[1000];
  int n,m,i,j,c=0;
  scanf("%d %d",&n,&m);
  for(i=0;i<n;i++){
    for(j=0;j<m;j++){
      scanf("%d",&a[i][j]);
    }
  }
  for(j=0;j<m;j++){
scanf("%d",&b[j]);
  }
  for(i=0;i<n;i++){
    for(j=0;j<m;j++){
      c+=a[i][j]*b[j];
    }
   printf("%d\n",c);
   c=0;
  
  } 
return 0;
}
/*
#include <iostream>
#include <stdio.h>
using namespace std;

int main(void) {
	int n, m;
	cin >> n >> m;
	int matrix[100][100];
	int vector[100];
	int answer[100];
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++)
			cin >> matrix[i][j];
	for (int i = 0; i < m; i++)
		cin >> vector[i];

	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++)
			answer[i] += matrix[i][j] * vector[j];

	for (int i = 0; i < m; i++) {
		cout << answer[i] << endl;
	}
	return 0;
}
*/


Compiler output:
a.cc:6:1: error: extended character   is not valid in an identifier
    6 |   int n,m,i,j,c=0;
      | ^
a.cc:6:1: error: extended character   is not valid in an identifier
a.cc:7:1: error: extended character   is not valid in an identifier
    7 |   scanf("%d %d",&n,&m);
      | ^
a.cc:7:1: error: extended character   is not valid in an identifier
a.cc:8:1: error: extended character   is not valid in an identifier
    8 |   for(i=0;i<n;i++){
      | ^
a.cc:8:1: error: extended character   is not valid in an identifier
a.cc:9:1: error: extended character   is not valid in an identifier
    9 |     for(j=0;j<m;j++){
      | ^
a.cc:9:1: error: extended character   is not valid in an identifier
a.cc:9:1: error: extended character   is not valid in an identifier
a.cc:9:1: error: extended character   is not valid in an identifier
a.cc:10:1: error: extended character   is not valid in an identifier
   10 |       scanf("%d",&a[i][j]);
      | ^
a.cc:10:1: error: extended character   is not valid in an identifier
a.cc:10:1: error: extended character   is not valid in an identifier
a.cc:10:1: error: extended character   is not valid in an identifier
a.cc:10:1: error: extended character   is not valid in an identifier
a.cc:10:1: error: extended character   is not valid in an identifier
a.cc:11:1: error: extended character   is not valid in an identifier
   11 |     }
      | ^
a.cc:11:1: error: extended character   is not valid in an identifier
a.cc:11:1: error: extended character   is not valid in an identifier
a.cc:11:1: error: extended character   is not valid in an identifier
a.cc:12:1: error: extended character   is not valid in an identifier
   12 |   }
      | ^
a.cc:12:1: error: extended character   is not valid in an identifier
a.cc:13:1: error: extended character   is not valid in an identifier
   13 |   for(j=0;j<m;j++){
      | ^
a.cc:13:1: error: extended character   is not valid in an identifier
a.cc:15:1: error: extended character   is not valid in an identifier
   15 |   }
      | ^
a.cc:15:1: error: extended character   is not valid in an identifier
a.cc:16:1: error: extended character   is not valid in an identifier
   16 |   for(i=0;i<n;i++){
      | ^
a.cc:16:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
   17 |     for(j=0;j<m;j++){
      | ^
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
   18 |       c+=a[i][j]*b[j];
      | ^
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
   19 |     }
      | ^
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:20:1: error: extended character   is not valid in an identifier
   20 |    printf("%d\n",c);
      | ^
a.cc:20:1: error: extended character   is not valid in an identifier
a.cc:20:1: error: extended character   is not valid in an identifier
a.cc:21:1: error: extended character   is not valid in an identifier
   21 |    c=0;
      | ^
a.cc:21:1: error: extended character   is not valid in an identifier
a.cc:21:1: error: extended character   is not valid in an identifier
a.cc:22:1: error: extended character   is not valid in an identifier
   22 |   
      | ^
a.cc:22:1: error: extended character   is not valid in an identifier
a.cc:23:1: error: extended character   is not valid in an identifier
   23 |   } 
      | ^
a.cc:23:1: error: extended character   is not valid in an identifier
a.cc:23:4: error: extended character   is not valid in an identifier
   23 |   } 
      |    ^
a.cc: In function 'int main()':
a.cc:6:1: error: '\U000000a0\U000000a0int' was not declared in this scope
    6 |   int n,m,i,j,c=0;
      | ^~~~~
a.cc:7:18: error: 'n' was not declared in this scope
    7 |   scanf("%d %d",&n,&m);
      |                  ^
a.cc:7:21: error: 'm' was not declared in this scope
    7 |   scanf("%d %d",&n,&m);
      |                     ^
a.cc:7:1: error: '\U000000a0\U000000a0scanf' was not declared in this scope
    7 |   scanf("%d %d",&n,&m);
      | ^~~~~~~
a.cc:8:7: error: 'i' was not declared in this scope
    8 |   for(i=0;i<n;i++){
      |       ^
a.cc:13:7: error: 'j' was not declared in this scope
   13 |   for(j=0;j<m;j++){
      |       ^
a.cc:23:4: error: '\U000000a0' was not declared in this scope
   23 |   } 
      |    ^