Disjoint Set in c

#include <stdio.h>

#define SIZE 100

struct edge{
    int u, v;
} E[SIZE];

struct disjointset
{
    int parent;
    int size;
    int rank;
} S[SIZE];

void get_edge_list(int m)
{
    int x, y;
    for(int i = 0; i< m; i++)
    {
        scanf("%d %d", &x, &y);
        E[i].u = x;
        E[i].v= y;
    }
}

void initialize_set(int n)
{
    for(int i = 0; i<n; i++)
    {
        S[i].rank = 0;
        S[i].parent = i;
        S[i].size = 1;
    }
}

int find_parent(int u)
{
    if(S[u].parent == u)
    {
        return u;
    }
    else
        return find_parent(S[u].parent);

}

void unions(int u, int v)
{
    if(S[u].rank > S[v].rank)
    {
        S[v].parent = u;
        S[u].size++;
    }
    else if(S[u].rank < S[v].rank)
    {
        S[u].parent = v;
        S[v].size++;
    }
    else{
        S[v].parent = u;
        S[u].rank ++;
        S[u].size++;

    }
}

void process_graph(int n, int m)
{
    int u, v;
    initialize_set(n);
    for(int i= 0; i<m; i++)
    {
        u = find_parent(E[i].u);
        v = find_parent(E[i].v);
        if ( u!= v)
            unions(u, v);
    }
}

int component_count(int n)
{
    int count = 0;
    for(int i = 0; i< n; i++)
    {
        if(S[i].parent == i)
            count++;
    }
    return count;
}

int largest_component_size(int n)
{
    int maz = 0;
    for(int i = 0; i<n; i++)
    {
        if(maz < S[i].size)
            maz = S[i].size;
    }
    return maz;
}

void parentNodes(int v)
{
    if(S[v].parent == v)
        return;
    else{
        printf("%d ", S[v].parent);
        return parentNodes(S[v].parent);
    }
}

void component_nodes(int n, int v)
{
    for(int i = 0; i<n; i++)
    {
        if(S[v].parent == S[i].parent)
        {
            printf("%d ", i);
        }
    }
}


int main()
{
    freopen("input.txt", "r", stdin);
    int n,m;
    scanf("%d %d", &n, &m);
    get_edge_list(m);
    process_graph(n, m);
    for(int i = 0; i< n; i++)
    {
        printf("%d have rank %d and parent %d and size %d\n", i, S[i].rank, S[i].parent, S[i].size);
    }
    printf("Total component %d\n", component_count(n));
    printf("Largest component size is %d\n", largest_component_size(n));
    parentNodes(2);
    printf("\n");
    component_nodes(n, 3);
    return 0;
}