disjoint set union

void initset(int n){
    for(int i = 1; i<=n; i++){
        ara[i] = i;
        sz[i] = 1;
    }
}

int findset(int i){
    if(ara[i] == i) return i;
    return ara[i] = findset(ara[i]);
}

bool issameset(int i, int j){
    return (findset(i)==findset(j));
}

void unionset(int i, int j){
    int a = findset(j);
    int b = findset(i);
    if(a==b) return;
    if(sz[a]>=sz[b]){
        sz[a]+=sz[b];
        ara[b] = a;
    }
    else{
        sz[b]+=sz[a];
        ara[a] = b;
    }
}