View Compilation Error

0_0_16382962_21298.cpp: In function 'int main()':
0_0_16382962_21298.cpp:4:567: error: 'reverse' was not declared in this scope
 int main (){     int n;    int i,j;    int len;    int pos=0;    while(scanf("%d",&n)!=EOF)    {          pos=0;        for(i=0;i<n;i++)            scanf("%s",matrix[i]);        len=strlen(matrix[0]);        int flag=0;        for(j=0;j<len;j++)        {            for(i=0;i<n;i++)            {                if(matrix[i][j]!='_')                    flag=1;                if(flag==1)                 {                    line[pos]=matrix[i][j];                    pos++;                }            }          }        line[pos]='\0';        reverse(line,line+pos);        for(i=0;i<pos;i++)        {            if(line[i]=='_')            {                printf(" ");                continue;            }            else if(line[i]=='\\')            {                printf("\n");                continue;            }            else                 printf("%c",line[i]);        }       printf("\n\n");    }    return 0;}
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