本人用的Dev_c++，在调代码时发现系统自动输出了s值，这是为什么？

#include<bits/stdc++.h>
int n, q, s;
int main(){
	scanf("%d", &n);
	for(int i(1), x; i <= n; i++){
		scanf("%d", &x); if(q < x) s += x - q, q = x;
	}
	exit(0);
}

#include<bits/stdc++.h>
int n, q, s;
int main(){
	scanf("%d", &n);
	for(int i(1), x; i <= n; i++){
		scanf("%d", &x); if(q < x) s += x - q, q = x;
	}
    printf("%d", s);
	exit(0);
}