Buggy python submission (verdict: Runtime Error):
import sys
s=input()
ans=0
i=0
j=len(s)-1
xi=0
yj=0
while(i<j):

    while(i<len(s) and s[i]=='x'):
        i+=1
        xi+=1
#        print(i,xi)

    while(j>=0 and s[j]=='x'):
        j-=1
        yj+=1
#        print(j,yj)

#    print(i,xi,j,yj)
    if(s[i]!=s[j]):
        print(-1)
        sys.exit()
    else:
        ans+=abs(xi-yj)
        xi=0
        yj=0
        i+=1
        j-=1

print(ans)

Fixed submission:
import sys
s=input()
ans=0
i=0
j=len(s)-1
xi=0
yj=0
while(i<j):

    while(i<len(s)-1 and s[i]=='x'):
        i+=1
        xi+=1
#        print(i,xi)

    while(j>0 and s[j]=='x'):
        j-=1
        yj+=1
#        print(j,yj)

#    print(i,xi,j,yj)
    if(s[i]!=s[j]):
        print(-1)
        sys.exit()
    else:
        ans+=abs(xi-yj)
        xi=0
        yj=0
        i+=1
        j-=1

print(ans)

Buggy python submission (verdict: Runtime Error):
import sys
s=input()
ans=0
i=0
j=len(s)-1
xi=0
yj=0
while(i<j):

    while(s[i]=='x'):
        i+=1
        xi+=1
#        print(i,xi)

    while(s[j]=='x'):
        j-=1
        yj+=1
#        print(j,yj)

#    print(i,xi,j,yj)
    if(s[i]!=s[j]):
        print(-1)
        sys.exit()
    else:
        ans+=abs(xi-yj)
        xi=0
        yj=0
        i+=1
        j-=1

print(ans)

Fixed submission:
import sys
s=input()
ans=0
i=0
j=len(s)-1
xi=0
yj=0
while(i<j):

    while(i<len(s)-1 and s[i]=='x'):
        i+=1
        xi+=1
#        print(i,xi)

    while(j>0 and s[j]=='x'):
        j-=1
        yj+=1
#        print(j,yj)

#    print(i,xi,j,yj)
    if(s[i]!=s[j]):
        print(-1)
        sys.exit()
    else:
        ans+=abs(xi-yj)
        xi=0
        yj=0
        i+=1
        j-=1

print(ans)

Buggy python submission (verdict: Runtime Error):
import sys
s=input()
ans=0
i=0
j=len(s)-1
xi=0
yj=0
while(i<j):

    while(s[i]=='x'):
        i+=1
        xi+=1
#        print(i,xi)

    while(s[j]=='x'):
        j-=1
        yj+=1
#        print(j,yj)

    print(i,xi,j,yj)
    if(s[i]!=s[j]):
        print(-1)
        sys.exit()
    else:
        ans+=abs(xi-yj)
        xi=0
        yj=0
        i+=1
        j-=1

print(ans)

Fixed submission:
import sys
s=input()
ans=0
i=0
j=len(s)-1
xi=0
yj=0
while(i<j):

    while(i<len(s)-1 and s[i]=='x'):
        i+=1
        xi+=1
#        print(i,xi)

    while(j>0 and s[j]=='x'):
        j-=1
        yj+=1
#        print(j,yj)

#    print(i,xi,j,yj)
    if(s[i]!=s[j]):
        print(-1)
        sys.exit()
    else:
        ans+=abs(xi-yj)
        xi=0
        yj=0
        i+=1
        j-=1

print(ans)

Buggy python submission (verdict: Runtime Error):
import sys
s=input()
ans=0
i=0
j=len(s)-1
xi=0
yj=0
while(i<j):

    while(s[i]=='x'):
        i+=1
        xi+=1
        print(i,xi)

    while(s[j]=='x'):
        j-=1
        yj+=1
        print(j,yj)

    print(i,xi,j,yj)
    if(s[i]!=s[j]):
        print(-1)
        sys.exit()
    else:
        ans+=abs(xi-yj)
        xi=0
        yj=0
        i+=1
        j-=1

print(ans)

Fixed submission:
import sys
s=input()
ans=0
i=0
j=len(s)-1
xi=0
yj=0
while(i<j):

    while(i<len(s)-1 and s[i]=='x'):
        i+=1
        xi+=1
#        print(i,xi)

    while(j>0 and s[j]=='x'):
        j-=1
        yj+=1
#        print(j,yj)

#    print(i,xi,j,yj)
    if(s[i]!=s[j]):
        print(-1)
        sys.exit()
    else:
        ans+=abs(xi-yj)
        xi=0
        yj=0
        i+=1
        j-=1

print(ans)

Buggy python submission (verdict: Runtime Error):
import sys
s=input()

s_nox=[]
x=[]
xcount=0
for si in list(s):
    if(si!='x'):
        x.append(xcount)
        xcount=0
        s_nox.append(si)
    else:
        xcount+=1
else:
    x.append(xcount)


for i in range((len(s_nox)//2)+1):
    j=-1*i -1
    if(s_nox[i] != s_nox[j]):
        print(-1)
        sys.exit()


ans=0
for i in range(len(x)//2):
    j=-1*i -1
    ans+=abs(x[i]-x[j])

if(len(x)%2==1 and x[len(x)//2]%2==1):
    ans+=1

print(ans)

Fixed submission:
import sys
s=input()
ans=0
i=0
j=len(s)-1
xi=0
yj=0
while(i<j):

    while(i<len(s)-1 and s[i]=='x'):
        i+=1
        xi+=1
#        print(i,xi)

    while(j>0 and s[j]=='x'):
        j-=1
        yj+=1
#        print(j,yj)

#    print(i,xi,j,yj)
    if(s[i]!=s[j]):
        print(-1)
        sys.exit()
    else:
        ans+=abs(xi-yj)
        xi=0
        yj=0
        i+=1
        j-=1

print(ans)