0分求助

#include<stdio.h>
#include<string.h>
char x[1001]={};
int main()
{
    int i,t=0,N,k,m=0,n=0,s,u=0,j;
    scanf("%d",&N);
    getchar();
    for(i=0;i<N;i++){
        fgets(x,1001,stdin);
        int l=strlen(x);
        //printf("%d",l);
        for(j=0;j<l;j++){
            if(x[j]>='0'&&x[j]<='9'&&t==0){
                m*=10;m+=x[j]-'0';
            }
            if(x[j-1]>='0'&&x[j-1]<='9'&&x[j]==' ') {
                t=1;
            }
            else if(x[j]>='0'&&x[j]<='9'&&t==1){
                n*=10;n+=x[j]-'0';
            }
        }
        if(x[0]=='a'){
            k=1;
            s=m+n;
            do{
            s/=10;u++;
            }while(s);
            s=m+n;
        }
        else if(x[0]=='b'){
            k=2;
            s=m-n;
            do{
            s/=10;u++;
            }while(s);
            s=m-n;
        }
        else if(x[0]=='c'){
            k=3;
            s=m*n;
            do{
            s/=10;u++;
            }while(s);
            s=m*n;
        }
        else{
            if(k==1){
            s=m+n;
            do{
                s/=10;u++;
            }while(s);
            s=m+n;
            }
            else if(k==2){
            s=m-n;
            do{
                s/=10;u++;
            }while(s);
            s=m-n;
            }
            else{
            s=m*n;
            do{
                s/=10;u++;
            }while(s);
            s=m*n;
            }
        }
        if(k==1) printf("%d+%d=%d\n",m,n,s);
        else if(k==2) printf("%d-%d=%d\n",m,n,s);
        else if(k==3) printf("%d*%d=%d\n",m,n,s);
        if(s<0){
            if(x[0]>='0'&&x[0]<='9') printf("%d\n",l+u+1);
        else printf("%d\n",l-1+u);
        }
        else{
                if(x[0]>='0'&&x[0]<='9') printf("%d\n",l+u);
        else printf("%d\n",l-2+u);
        }
        u=0;t=0;m=0;n=0;
    }
    return 0;
}