rt，刚学笛卡尔树，这个题被卡的RE+MLE,求查错/kel，码风不好，请见谅......

#include <algorithm>
// #include <iostream>
// #include <cstring>
#include <cstdio>
// #include <cmath>
#include <stack>
// using namespace std;

// #define int long long

/***************快读***************/

namespace IO {
char buf[1<<21], *p1 = buf, *p2 = buf, buf1[1<<21];
inline char gc () {return p1 == p2 && (p2 = (p1 = buf) + fread (buf, 1, 1 << 21, stdin), p1 == p2) ? EOF : *p1++;}

#ifndef ONLINE_JUDGE
#endif

#define gc getchar

template<class I>
inline void read(I &x) {
    x = 0; I f = 1; char c = gc();
    while(c < '0' || c > '9') {if(c == '-') f = -1; c = gc(); }
    while(c >= '0' && c <= '9') {x = x * 10 + c - '0'; c = gc(); }
    x *= f;
}

template<class I>
inline void write(I x) {
    if(x == 0) {putchar('0'); return;}
    I tmp = x > 0 ? x : -x;
    if(x < 0) putchar('-');
    register int cnt = 0;
    while(tmp > 0) {
        buf1[cnt++] = tmp % 10 + '0';
        tmp /= 10;
    }
    while(cnt > 0) putchar(buf1[--cnt]);
}

#define in(x) read(x)
#define outn(x) write(x), putchar('\n')
#define out(x) write(x), putchar(' ')

} using namespace IO;

/***************快读***************/

#define maxn 5000010

int n,m,seed;
int root;

struct Descartes_Fold{
	struct Des_Tree{
		int son[2];
		int val;
	}tree[maxn<<1];

	std::stack<int> Stack;
	int now,pos;

	inline void insert(register int ID){
		now=pos;
		register int rest;
		while(now&&tree[Stack.top()].val<tree[ID].val){
			rest=Stack.top();
			Stack.pop();
			--now;
		}
		if(now){tree[Stack.top()].son[1]=ID;}
		else{root=ID;}
		if(now<pos){tree[ID].son[0]=rest;}
		pos=++now;
		Stack.push(ID);
	}

	inline void work(){
		register int ans=0,res=0;
		for(register int i=1;i<=n;++i){
			ans^=i*(tree[i].son[0]+1);
			res^=i*(tree[i].son[1]+1);
		}
		out(ans),outn(res);
	}

	inline void dfs(register int now){
		if(now){
			out(now);
			dfs(tree[now].son[0]);
			dfs(tree[now].son[1]);
		}
	}
}sc;

struct LCA_Fold{
	int top[maxn],tot[maxn],depth[maxn];
	int id[maxn],son[maxn],fa[maxn];
	int dfs_cnt;

	inline int dfs1(register int now,register int f,register int dep){
		depth[now]=dep;
		fa[now]=f;
		tot[now]=1;
		register int maxson=-1;
		for(register int i=0;i<=1;++i){
			if(!sc.tree[now].son[i]){continue;}
			tot[now]+=dfs1(sc.tree[now].son[i],now,dep+1);
			if(maxson<tot[sc.tree[now].son[i]]){
				maxson=tot[sc.tree[now].son[i]];
				son[now]=sc.tree[now].son[i];
			}
		}
		return tot[now];
	}

	inline void dfs2(register int now,register int topf){
		id[now]=++dfs_cnt;
		top[now]=topf;
		if(!son[now]){return;}
		dfs2(son[now],topf);
		for(register int i=0;i<=1;i++){
			if(!sc.tree[now].son[i]){continue;}
			if(id[sc.tree[now].son[i]]){continue;}
			dfs2(sc.tree[now].son[i],sc.tree[now].son[i]);
		}
	}

	inline int LCA(register int x,register int y){
		while(top[x]!=top[y]){
			if(depth[top[x]]<depth[top[y]]){std::swap(x,y);}
			x=fa[top[x]];
		}
		if(depth[x]>depth[y]){std::swap(x,y);}
		return sc.tree[x].val;
	}
}lca;

/**data**/

namespace GenHelper{
    unsigned z1,z2,z3,z4,b;
    unsigned rand_()
    {
    b=((z1<<6)^z1)>>13;
    z1=((z1&4294967294U)<<18)^b;
    b=((z2<<2)^z2)>>27;
    z2=((z2&4294967288U)<<2)^b;
    b=((z3<<13)^z3)>>21;
    z3=((z3&4294967280U)<<7)^b;
    b=((z4<<3)^z4)>>12;
    z4=((z4&4294967168U)<<13)^b;
    return (z1^z2^z3^z4);
    }
}

void srand(unsigned x){
	using namespace GenHelper;
	z1=x; z2=(~x)^0x233333333U; z3=x^0x1234598766U; z4=(~x)+51;
}

inline int read_(){
    using namespace GenHelper;
    register int a=rand_()&32767;
    register int b=rand_()&32767;
    return a*32768+b;
}

/**data**/

int /*signed*/ main(){
	read(n),read(m),read(seed);
	srand(seed);
	for(register int i=1,u;i<=n;++i){
		sc.tree[i].val=read_();
		sc.insert(i);
	}
	lca.dfs1(root,0,1);
	lca.dfs2(root,root);
	register int u,v;
	unsigned long long ans=0;
	while(m--){
		u=read_(),v=read_();
		u=u%n+1,v=v%n+1;
		if(u>v){std::swap(u,v);}
		ans+=lca.LCA(u,v);
	}
	outn(ans);
	return 0;
}