RT求调，本地读入到第一个y就卡住了，看了一遍也没return，很不解

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define lowbit(x) x&(-x)
ll n,q,a[500005];
ll c[500005];
void add(ll x,ll v){
	for(ll i=x;i<=n;i+=lowbit(i)){
		c[i]+=v;
	}
}
ll ask(ll x){
	ll res=0;
	for(ll i=x;i>=1;i-=lowbit(i)){
		res+=c[i];
	}
	return res;
}
int main(){
	cin>>n;
	cin>>q;
	//scanf("%lld%lld",&n,&q);
	for(ll i=1;i<=n;++i) a[i]=0;
	for(ll i=1;i<=n;++i) add(i,a[i]);
	while(q--){
		char op;
		ll x,y;
		scanf("%c%lld%lld",&op,&x,&y);
		if(op=='x'){
			add(x,y);
		}
		if(op=='y'){
			printf("%lld\n",ask(y)-ask(x-1));
		}
	}
	return 0;
}