为什么编译失败

#include<iostream>
#include<cstring>
using namespace std;
char s[200];
int sum;
int main(){
	char s[200];
	int sum;
	gets(s);
	int n = strlen(s);
	for(int i = 0; i<n; i++){
		if(s[i]=='a'||s[i]=='d'||s[i]=='g'||s[i]=='j'||s[i]=='m'||s[i]=='p'||s[i]=='t'||s[i]=='w'||s[i]==' ') sum+=1;
		else if(s[i]=='b'||s[i]=='e'||s[i]=='h'||s[i]=='k'||s[i]=='n'||s[i]=='q'||s[i]=='u'||s[i]=='x') sum+=2;
		else if(s[i]=='c'||s[i]=='f'||s[i]=='i'||s[i]=='l'||s[i]=='o'||s[i]=='r'||s[i]=='v'||s[i]=='y') sum+=3;
		else if(s[i]=='s'||s[i]=='z') sum+=4;
	}
	cout<<sum<<endl;
	return 0;
}