Problem number 04

#include<stdio.h>
int main()
{
    int r,c,m,n,i;
    printf("[?]*[?] = \n");
    scanf("%d%d",&m,&n);
    int mat[m][n];
    for (r=0;r<m;r++)
    {
        for (c=0;c<n;c++)
        {
            mat[r][c]=0;
        }
    }
    int num;
    printf("Number of edges = \n");
    scanf("%d",&num);
    printf("Enter edges = \n");
    for (r=0;r<num;r++){
        int u,v;
        scanf("%d %d",&u,&v);
        mat[u][v]=1;
        mat[v][u]=1;
    }
    for (r=0;r<m;r++)
    {
        for(i=0;i<m;i++)
        {printf("---|");}
        printf("\n");
        for(c=0;c<n;c++)
        {
            printf(" %d |",mat[r][c]);
        }
        printf("\n");
    }
     for(i=0;i<m;i++)
        {printf("---|");}
        printf("\n");
    return 0;
}