Language: C

#include <stdio.h>
int main(void)
    int n, m, l;
    scanf("%d %d %d", &n, &m, &l);
    int A[n][m], B[m][l];
    long long int C[n][l];
    
    int i, j;
    for(i=0; i<n; i++){
        for(j=0; j<m; j++){
            scanf("%d", &A[n][m]);
        }
    }
    
    int i, j;
    for(i=0; i<m; i++){
        for(j=0; j<l; j++){
            scanf("%d", &B[m][l]);
        }
    }
    
    int i, j, k;
    for(i=0; i<n; i++){
        for(k=0; k<m; k++){
            for(j=0; j<l; j++){
                C[i][k]+=A[i][j]*B[j][k];
            }
        }
    }
    
    int i, j;
    for(i=0; i<n; i++){
        for(j=0; j<l-1; j++){
            printf("%lld ", C[i][j]);
        }
        printf("%lld\n", C[i][l-1]);
    }
    
    
    return 0;
}


Compiler output:
main.c: In function 'main':
main.c:4:5: error: expected declaration specifiers before 'scanf'
    4 |     scanf("%d %d %d", &n, &m, &l);
      |     ^~~~~
main.c:9:5: error: expected declaration specifiers before 'for'
    9 |     for(i=0; i<n; i++){
      |     ^~~
main.c:9:14: error: expected declaration specifiers before 'i'
    9 |     for(i=0; i<n; i++){
      |              ^
main.c:9:19: error: expected declaration specifiers before 'i'
    9 |     for(i=0; i<n; i++){
      |                   ^
main.c:15:9: error: redefinition of parameter 'i'
   15 |     int i, j;
      |         ^
main.c:8:9: note: previous definition of 'i' with type 'int'
    8 |     int i, j;
      |         ^
main.c:15:12: error: redefinition of parameter 'j'
   15 |     int i, j;
      |            ^
main.c:8:12: note: previous definition of 'j' with type 'int'
    8 |     int i, j;
      |            ^
main.c:16:5: error: expected declaration specifiers before 'for'
   16 |     for(i=0; i<m; i++){
      |     ^~~
main.c:16:14: error: expected declaration specifiers before 'i'
   16 |     for(i=0; i<m; i++){
      |              ^
main.c:16:19: error: expected declaration specifiers before 'i'
   16 |     for(i=0; i<m; i++){
      |                   ^
main.c:22:9: error: redefinition of parameter 'i'
   22 |     int i, j, k;
      |         ^
main.c:15:9: note: previous definition of 'i' with type 'int'
   15 |     int i, j;
      |         ^
main.c:22:12: error: redefinition of parameter 'j'
   22 |     int i, j, k;
      |            ^
main.c:15:12: note: previous definition of 'j' with type 'int'
   15 |     int i, j;
      |            ^
main.c:23:5: error: expected declaration specifiers before 'for'
   23 |     for(i=0; i<n; i++){
      |     ^~~
main.c:23:14: error: expected declaration specifiers before 'i'
   23 |     for(i=0; i<n; i++){
      |              ^
main.c:23:19: error: expected declaration specifiers before 'i'
   23 |     for(i=0; i<n; i++){
      |                   ^
main.c:31:9: error: redefinition of parameter 'i'
   31 |     int i, j;
      |         ^
main.c:22:9: note: previous definition of 'i' with type 'int'
   22 |     int i, j, k;
      |         ^
main.c:31:12: error: redefinition of parameter 'j'
   31 |     int i, j;
      |            ^
main.c:22:12: note: previous definition of 'j' with type 'int'
   22 |     int i, j, k;
      |            ^
main.c:32:5: error: expected declaration specifiers before 'for'
   32 |     for(i=0; i<n; i++){
      |     ^~~
main.c:32:14: error: expected declaration specifiers before 'i'
   32 |     for(i=0; i<n; i++){
      |              ^
main.c:32:19: error: expected declaration specifiers before 'i'
   32 |     for(i=0; i<n; i++){
      |                   ^
main.c:40:5: error: expected declaration specifiers before 'return'
   40 |     return 0;
      |     ^~~~~~
main.c:41:1: error: expected declaration specifiers before '}' token
   41 | }
      | ^
main.c:2:5: error: old-style parameter declarations in prototyped function definition
    2 | int main(void)
      |     ^~~~
main.c:42: error: expected '{' at end of input