记录传送门

#include<bits/stdc++.h>
using namespace std;
int a,b,c;
char chr,ch1;
int read1(){
	int x=0;
	char ch=getchar();
	while(ch!='+'&&ch!='-'&&ch!='*'&&ch!='/'){
		while(ch>='0'&&ch<='9'){
			x=x*10+ch-'0';
			ch=getchar();
		}
		if(ch=='?'){
			return -1;
		}
		if(ch=='+'||ch=='-'||ch=='*'||ch=='/'){
			break;
		}
		ch=getchar();
		ch1=ch;
	}
	chr=ch;
	return x;
}
int read2(){
	int x=0;
	char ch=ch1;
	while(ch!='='){
		while(ch>='0'&&ch<='9'){
			x=x*10+ch-'0';
			ch=getchar();
		}
		if(ch=='?'){
			return -1;
		}
		if(ch=='='){
			break;
		}
		ch=getchar();
		ch1=ch;
	}
	return x;
}
int read3(){
	int x=0;
	char ch=getchar();
	while(ch<'0'||ch>'9'){
		if(ch=='?'){
			return -1;
		}
		ch=getchar();
	}
	while(ch>='0'&&ch<='9'){
		x=x*10+ch-'0';
		ch=getchar();
		while(ch==' ')ch=getchar();
	}
	return x;
}
int main(){
	int a=read1(),b=read2(),c=read3();
	double ansa,ansb,ansc;
//	cout<<a<<' '<<chr<<' '<<b<<' '<<c<<'\n';
	if(chr=='+'){
		if(a==-1){
			cout<<c-b<<".00";
		}else if(b==-1){
			cout<<c-a<<".00";
		}else if(c==-1){
			cout<<a+b<<".00";
		}
	}else if(chr=='-'){
		if(a==-1){
			cout<<c+b<<".00";
		}else if(b==-1){
			cout<<a-c<<".00";
		}else if(c==-1){
			cout<<a-b<<".00";
		}
	}else if(chr=='*'){
		if(a==-1){
			ansa=1.0*c/b;
			printf("%.2f",ansa);
		}else if(b==-1){
			ansb=1.0*c/a;
			printf("%.2f",ansb);
		}else if(c==-1){
			cout<<a*b<<".00";
		}
	}else if(chr=='/'){
		if(a==-1){
			cout<<b*c<<".00";
		}else if(b==-1){
			ansb=1.0*a/c;
			printf("%.2f",ansb);
		}else if(c==-1){
			ansc=1.0*a/b;
			printf("%.2f",ansc);
		}
	}
	return 0;
}