Devc++样例全过了，但是0分

#include<bits/stdc++.h>
using namespace std;
string py;
int main() {
	int n;
	cin>>n;
	string s1, s2, s3;
	for(int i=0; i<2*n; i++) {
		cin>>s1;
		if(s1=="a") {
			py="+";
			cin>>s2>>s3;
			int sum=stoi(s2)+stoi(s3);
			string s4=to_string(sum);
			string ss=s2+"+"+s3+"="+s4;
			printf("%d+%d=%d\n%d\n", stoi(s2), stoi(s3), sum, ss.size());
		} else if(s1=="c") {
			py="*";
			cin>>s2>>s3;
			int sum=stoi(s2)*stoi(s3);
			string s4=to_string(sum);
			string ss=s2+"*"+s3+"="+s4;
			printf("%d*%d=%d\n%d\n", stoi(s2), stoi(s3), sum, ss.size());
		} else if(s1=="b") {
			py="-";
			cin>>s2>>s3;
			int sum=stoi(s2)-stoi(s3);
			string s4=to_string(sum);
			string ss=s2+"-"+s3+"="+s4;
			printf("%d-%d=%d\n%d\n", stoi(s2), stoi(s3), sum, ss.size());
		} else {
			if(py=="+") {
				cin>>s2;
				int sum=stoi(s1)+stoi(s2);
				string s3=to_string(sum);
				string ss=s1+"+"+s2+"="+s3;
				printf("%d+%d=%d\n%d\n", stoi(s1), stoi(s2), sum, ss.size());
			} else if(py=="*") {
				cin>>s2;
				int sum=stoi(s1)*stoi(s2);
				string s3=to_string(sum);
				string ss=s1+"*"+s2+"="+s3;
				printf("%d*%d=%d\n%d\n", stoi(s1), stoi(s2), sum, ss.size());
			} else if(py=="-") {
				cin>>s2;
				int sum=stoi(s1)-stoi(s2);
				string s4=to_string(sum);
				string ss=s1+"-"+s2+"="+s3;
				printf("%d-%d=%d\n%d\n", stoi(s1), stoi(s2), sum, ss.size());
			}
		}
	}

}