下载的样例对但是全WA，是什么问题？

#include <bits/stdc++.h>
#include <cstdio>
#include <cstring>
#include <iostream>

using namespace std;
char s[60][30];
int n,f,a,b,c,k,ok,ans;
int main()
{
	scanf("%d",&n); s[0][0]=getchar();
	for (int i=1;i<=n;i++)
		gets(s[i]);
	for (int i=1;i<=n;i++) {
		for (int j=0;j<strlen(s[i]);j++) {
			if (s[i][j]=='a') {
				f=1;continue;
			}
			if (s[i][j]=='b') {
				f=2;continue;}
			if (s[i][j]=='c') {
				f=3;continue;}
			if (s[i][j]==' ' and a!=0) {
				ans+=k;k=0;ok=1;continue;}
			if (s[i][j]==' ') {
				k=0;continue;}
			k++;
			if (ok==0) {
				a*=10; a+=(s[i][j]-'0');
			}
			if (ok==1) {
				b*=10; b+=(s[i][j]-'0');
			}
		}
		ans+=k;
		if (f==1) {
			cout<<a<<"+"<<b<<"="<<a+b<<endl;
			c=a+b;
		}
		if (f==2) {
			cout<<a<<"-"<<b<<"="<<a-b<<endl;
			c=a-b;
			if (c<0) {
				ans++;
				c=-c;
			}
		}
		if (f==3) {
			cout<<a<<"*"<<b<<"="<<a*b<<endl;
			c=a*b; 
		}
		
		while (c>0) {
			c/=10;
			ans++;
		}
		cout<<ans+2<<endl;
//		cout<<ans<<" "<<a<<" "<<b<<endl; 
		ok=0;
		ans=0;
		k=0;
		a=0;
		b=0;
		c=0;
	}
	return 0;
}