TWOSTR problem beginner section,showing WA .I'm not getting which test case it doesn't satisfy? so, please help

#include <stdio.h>
#include <stdlib.h>
#include<string.h>
int main()
{int t,i;
char x[20],y[20];
scanf("%d",&t);
while(t–)
{
scanf("%s",x);
scanf("%s",y);
int c=0,j=strlen(x);
for(i=1;i<=j;i++)
{
if((x[i]==’?’)||(y[i]==’?’))
{
c++;
}
}
int k=0;
for(i=1;i<=j;i++)
{
if(((x[i]!=’?’)||(y[i]!=’?’))&&(x[i]==y[i]))
{
k++;
}

    }
    if(k==(j-c))
    {
        printf("Yes\n");
    }
    else
    {
        printf("No\n");
    }

}
return 0;

}

i got it, indexing should be done from 0 to n-1;

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