注意：没有合并多项式的功能，且未知数必须只在左边，右边是常数！！！

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代码如下：

#include<iostream>
#include<stdio.h>

using namespace std;

string q,f;double a,b,c;bool bsz=0;

/*string addSame(string ba){
	for(int i=0;i<int(ba.length());i++)
		if(ba[i]>='a'&&ba[i]<='z')
			ba[i]='x';
	if(ba[0]!='-')ba=string("+")+ba;
	string side,nba=ba;
	for(int i=0;i<int(nba.length());i++){
		if(nba[i]=='-'||nba[i]=='+'){
			side+=string(1,nba[i]);
		}
		if(nba[i]=='-'){
			nba[i]='+';
		}
	}
	string vs[side.length()];
	int df=-1;
	for(int i=0;i<int(nba.length());i++){
		if(nba[i]=='+'){
			df++;
		}else{
			vs[df]+=string(1,nba[i]);
		}
	}
	double xnum=0,cnum=0;double j;
	for(int i=0;i<int(side.length());i++){
		if(vs[i][vs[i].length()-1]=='x'){
			sscanf(vs[i].data(),"%lfx",&j);
			xnum+=j;
		}else{
			sscanf(vs[i].data(),"%lf",&j);
			cnum+=j;
		}
	}
	char cstr[64];
	sprintf(cstr,"%c%lfx%c%lf",(xnum>=0?'+':0),xnum,(cnum>=0?'+':0),cnum);
	return string(cstr);
}*/

string getS(string &str){
	string ret="";
	if(str[0]=='+'){
		str[0]=' ';
	}else if(str[0]=='-'){
		str[0]=' ';
		bsz=1;
	}
	for(int i=0;i<int(str.length());i++){
		if(str[i]=='+'||str[i]=='-'){
			ret+=string(1,str[i]);
		}else if(str[i]=='='){
			return ret;
		}else if(str[i]>='a'&&str[i]<='z'){
			ret+=string(1,'x');
			str[i]='x';
		}
	}
	throw "can not know";
}

void getD(string str){
	if(str=="x+"){
		sscanf(q.data(),"%lfx+%lf=%lf",&a,&b,&c);
		if(bsz)a=-a;
	}else if(str=="+x"){
		sscanf(q.data(),"%lf+%lfx=%lf",&b,&a,&c);
		if(bsz)b=-b;
	}else if(str=="x"){
		if(q[0]=='x'){
			sscanf(q.data(),"x=%lf",&c);
			a=1;b=0;
			if(bsz)a=-a;
			return;
		}
		sscanf(q.data(),"%lfx=%lf",&a,&c);
		b=0;
		if(bsz)a=-a;
	}else if(str=="x-"){
		sscanf(q.data(),"%lfx-%lf=%lf",&a,&b,&c);
		b=-b;
		if(bsz)a=-a;
	}else if(str=="-x"){
		sscanf(q.data(),"%lf-%lfx=%lf",&b,&a,&c);
		a=-a;
		if(bsz)b=-b;
	}
}

double know(double a,double b,double c){
	return (c-b)/a;
}

/*double solution(string bk){
	string bs="",es="";bool isnis=1;
	for(int i=0;i<int(bk.length());i++){
		if(bk[i]=='='){
			isnis=0;
		}
		if(isnis){
			bs+=string(1,bk[i]);
		}else{
			es+=string(1,bk[i]);
		}
	}
	bs=addSame(bs);
	bk=bs+es;
	getD(getS(bk));
	return -know(a,b,c);
}*/
double solution(string bk){
	getD(getS(bk));
	return know(a,b,c);
}

char getnk(string bf){
	char r=0;
	for(int i=0;i<int(bf.length());i++){
		if(bf[i]>='a'&&bf[i]<='z'){
			r=bf[i];
			break;
		}
	}
	return r;
}

int main(){
	cin>>q;
	cout<<getnk(q)<<'='<<solution(q);
}